A socket includes a socket body having a mounting part, and a holding lever supported on the mounting part to hold a relay mounted at a mounting position of the mounting part. The holding lever includes a support, and a stopper provided on the support and movable between a restriction position at which movement of the relay, positioned at the mounting position, in a removing direction is restricted and a restriction release position at which the restriction of the movement of the relay in the removing direction is released. The holding lever is supported on the mounting part to be movable between a retreat position at which a relay can be mounted and removed and a holding position at which a relay positioned at the mounting position can be held when the stopper is positioned at the restriction position such that the stopper covers a center-of-gravity position of the relay.