An endoscope apparatus 1 includes: an endoscope connector 20 a first optical connector 51 extended from a plug section 41 first insertion openings 71 and 76 of a receptacle section 31 into which the first optical connector 51 is inserted second insertion openings 72 and 77 of the receptacle section 31 into which a second optical connector 52 is inserted a wrong insertion preventing member 74 that is partially located in the second insertion openings 72 and 77, and is moved, in conjunction with insertion of the first optical connector 51 into the first insertion openings 71 and 76, to a retracted position at which the second optical connector 52 is insertable into the second insertion openings 72 and 77 and a contact member 78 that comes into contact with the wrong insertion preventing member 74 when the first optical connector 51 is inserted into the second insertion openings 72 and 77.
