If a user pushes an operating member 50 in a state in which a case 11 of an optical transceiver 1 is locked in a cage 2, a lever 22 is turned to the front of the optical transceiver 1. If the user pulls out the turned lever 22, a projection provided on an actuating piece 28 abuts a convex portion 35 so that an end of the actuating piece 28 projects below the case 11. If a plate spring portion 18 of the cage 2 is pressed and elastically displaced by the end of the actuating piece 28, a lock portion 17 of the case 11 comes off a locking hole 19 of the plate spring portion 18, and the optical transceiver 1 can be pulled out of the cage 2.