linear groove line along a direction of an optical axis for guiding when the lc type optical connector plugs p 1 and p 2 are inserted each of the guide protrusion 7 a and the concave groove portion 7 b constructs a guide groove line described in each of claims as shown in fig1 to 9 an arc shaped notch portion 1 d is formed in an upper end of the one fitting portion a of the connector housing 1 which is employed in the embodiment mentioned above further in place of the insertion of the lc type optical connector plug p 2 into the other fitting portion b the other optical part for example the sc type optical connector plug or the other plug may be inserted a shutter plate 11 for closing the fitting portion a in a diagonal arrangement is arranged in the one fitting portion a of the connector housing 1 so that the shutter plate can be opened and closed in an inner side in other words the shutter plate 11 is structured such that a support shaft 15 is integrally provided in a protruding manner at a horizontal position of its lower end and protruding portions 15 a provided in symmetrical positions in both ends of the support shaft 15 are rotatably supported to a shaft hole 16 which is formed over the bottom wall 1 c at the right and left opposed positions of the lower portion of the fitting end of the fitting portion a and the.