moved out of this hole in a direction opposite to this inserting direction guide grooves 25 for respectively guiding guide members 26 of the bolt holder portion 2 are formed in that portion surrounding that portion at which the nut 22 is embedded next the fitting of the first and second connector housings 6 and 20 as well as an indication operation will be described front end portions of the guide members 26 formed on the bolt holder portion 2 of the first connector housing 6 are inserted respectively in the guide grooves 25 formed in the second connector housing 20 thereby achieving a provisionally retained condition as shown in fig1 in this condition a front end of a threaded portion 21 of the bolt is held against a peripheral edge of the nut 22 so that the bolt can be threaded into the nut the indicator 11 is held in a provisionally retained condition with each stopper 15 held against a step 6a formed at the end of the associated guide groove 9 in the first connector housing 6 in this condition the indicator cannot be withdrawn the fitting confirmation portion 14 is disposed immediately adjacent to the inner surface of the projection 8 and can not be viewed with the eyes through the window portion 7 and the indicator 11 is spaced apart from the retaining projection 23 then in the provisionally retained condition when the bolt 3 is threaded the two connector housings 6 and 20 are moved toward each other and the retaining projection.