FIG. 13 illustrates the configuration of a type of connector device of the related art described in PTL 1. The connector device includes a first connector housing 110 which is mounted in a mounting hole Pa of a panel P from one side in a direction perpendicular to the panel P, and a second connector housing 160 which is fitted to the first connector housing 110 with the panel P interposed therebetween through the mounting hole Pa from the other side in the direction perpendicular to the panel P.
In the connector housings 110 and 160, terminal metal fittings (not illustrated) which are electrically connected to each other when the two connector housings 110 and 160 are fitted to each other are respectively accommodated. A first connector is constituted by the first connector housing 110 and the terminal metal fittings accommodated in the first connector housing 110. In addition, a second connector is constituted by the second connector housing 160 and the terminal metal fittings accommodated in the second connector housing 160.
The first connector housing 110 is provided with temporary locking arms 112. The temporary locking arms 112 include locking protrusions 113. When the first connector housing 110 is inserted into the mounting hole Pa of the panel P from the one side, the temporary locking arm 112 is bent inward from the initial positions by coming into sliding contact with the peripheral edge of the mounting hole Pa. In addition, when the first connector housing 110 is further inserted to a predetermined position, the temporary locking locking arm 112 returns to the initial position from the bent position such that the locking protrusion 113 is locked to the peripheral edge of the mounting hole Pa. Accordingly, the temporary locking arm 112 temporarily locks the first connector housing 110 to the mounting hole Pa of the panel P in a state of impeding the movement of the first connector housing 110 toward the one side.
The second connector housing 160 is provided with complete fixing portions 170 which are locked to the peripheral edge of the mounting hole Pa of the panel P to allow the second connector housing 160 to be completely fixed to the panel P. In addition, the second connector housing 160 is provided with temporary locking releasing portions 180, which, when the second connector housing 160 is fitted to the first connector housing 110 in the state where the locking protrusions 113 of the temporary locking arms 112 are locked to the mounting hole Pa of the panel P, allow the temporary locking arm 112 to be bent inward during the fitting operation and thus release the locking of the temporary locking arms 112 to the mounting hole Pa of the panel P.
In addition, main locking portions 190 which allow the first connector housing 110 and the second connector housing 160 to be locked to each other when the first connector housing 110 and the second connector housing 160 are completely fitted to each other are provided between the first connector housing 110 and the second connector housing 160.
The main locking portions 190 include locking arms 191 provided in the first connector housing 110 and stepped portions 192 provided in the second connector housing 160. The stepped portion 192 is provided by concavely forming an inclined surface which is increased in height moving toward the rear side, and the rear end portion thereof serves as a locking portion. The tip end of the locking arm 191 is provided with a lower surface engagement protrusion 191a and an upper surface engagement protrusion 191b. 
When the second connector housing 160 is fitted to the first connector housing 110, part-way during the fitting, the lower surface engagement protrusion 191a of the locking arm 191 and the stepped portion 192 interfere with each other. Due to the interference, the locking arm 191 is bent outward from the initial position. In addition, when the fitting further proceeds and then a completely fitted state is achieved, the locking arm 191 returns to the initial position from the bent position. Accordingly, the lower surface engagement protrusion 191a of the locking arm 191 is engaged with the rear end portion of the stepped portion 192 such that the first connector housing 110 and the second connector housing 160 are locked to each other.
When the second connector housing 160 is fitted to the first connector housing 110 in a state where the tip end of the locking arm 191 is inserted into the mounting hole Pa of the panel P and the lower surface engagement protrusion 191a of the locking arm 191 and the stepped portion 192 interfere with each other part-way during the fitting so as to cause the locking arm 191 to be bent outward, the upper surface engagement protrusion 191b of the locking arm 191 interferes with panel P such that the locking arm 191 and the stepped portion 192 restrict the movement of the first connector housing 110 relative to the panel P until the first connector housing 110 and the second connector housing 160 are completely fitted to each other. In addition, in a state where the first connector housing 110 and the second connector housing 160 are completely fitted to each other, the upper surface engagement protrusion 191b of the locking arm 191 which returns to the initial position from the bent position comes away from the position that interferes with the panel P such that the locking arm 191 and the stepped portion 192 also function as movement restricting and allowing portions 195 which allow the movement of the first connector housing 110 relative to the panel P.
In a case of using the connector device, first, the first connector housing 110 is mounted in the mounting hole Pa of the panel P from the one side in the direction perpendicular to the panel P. At this time, as the tip end of the temporary locking arm 112 is inserted into the mounting hole Pa, the locking protrusion 113 of the temporary locking arm 112 comes into sliding contact with the peripheral edge of the mounting hole Pa such that the temporary locking arm 112 is bent inward. When the tip end of the temporary locking arm 112 is further inserted to a predetermined position, the temporary locking arm 112 returns to the initial position from the bent position such that the locking protrusion 113 of the temporary locking arm 112 is locked to the peripheral edge of the mounting hole Pa of the panel P. Accordingly, the first connector housing 110 is temporarily locked to the panel P.
Subsequently, the second connector housing 160 is fitted from the opposite side of the panel P to the first connector housing 110 in the state where the locking protrusion 113 of the temporary locking arm 112 is locked to the mounting hole Pa of the panel P. Then, the temporary locking releasing portion 180 allows the temporary locking arm 112 to be bent inward as the fitting operation proceeds such that the locking of the locking protrusion 113 of the temporary locking arm 112 to the mounting hole Pa of the panel P is released.
In addition, during the operation of fitting the second connector housing 160 to the first connector housing 110, the lower surface engagement protrusion 191a of the locking arm 191 on the first connector housing, which is included in the main locking portion 190, rides on the stepped portion 192 on the second connector housing 160 side which is the opposite side to the panel P (that is, the second connector housing 160 side). Accordingly, the locking arm 191 is bent outward such that the upper surface engagement protrusion 191b of the locking arm 191 is engaged with the peripheral edge of the mounting hole Pa of the panel P. As a result, the first connector housing 110 is restricted so as not to move relative to the panel P. Therefore, the second connector housing 160 can be fitted to the first connector housing 110 in the state of being fixed to the panel P.
When the second connector housing 160 is completely fitted to the first connector housing 110, the lower surface engagement protrusion 191a of the locking arm 191 of the main locking portion 190 is placed over the stepped portion 192, the locking arm 191 returns to the initial position from the bent position, and the lower surface engagement protrusion 191a is engaged with the rear end portion of the stepped portion 192. Accordingly, the first connector housing 110 and the second connector housing 160 are locked to each other.
In this state, as the locking arm 191 returns to the initial position from the bent position, the upper surface engagement protrusion 191b of the locking arm 191 comes away from the position that is engaged with the peripheral edge of the mounting hole Pa of the panel P, and thus the first connector housing 110 can move relative to the panel P. Therefore, by pushing the second connector housing 160 fitted to the first connector housing 110 against the panel P, the complete fixing portion 170 provided in the second connector housing 160 can be locked to the peripheral edge of the mounting hole Pa of the panel P. Accordingly, the second connector housing 160 and the first connector housing 110 can be completely fixed to the panel P.