A socket comprising: a socket body including a mounting part on which a relay is to be mounted in a mounting direction; and a holding lever supported on the mounting part of the socket body and configured to hold the relay mounted at a mounting position of the mounting part, wherein the holding lever includes: a support extending from the mounting part of the socket body in a removing direction opposite to the mounting direction; and a stopper provided on an end part of the support distal to the socket body in the removing direction and configured to restrict movement of the relay, positioned at the mounting position, in the removing direction, the stopper is provided on the support and configured to move between a restriction position and a restriction release position, wherein at the restriction position, the stopper restricts movement of the relay, positioned at the mounting position, in the removing direction from the mounting part, and wherein at the restriction release position, the stopper releases the restriction of the movement of the relay, positioned at the mounting position, in the removing direction from the mounting part, and the holding lever is supported on the mounting part and configured to move between a retreat position and a holding position, wherein at the retreat position, when the stopper is positioned at the restriction release position, a relay can be mounted at the mounting position of the mounting part and the relay mounted at mounting position can be removed, and wherein at the holding position, the relay positioned at the mounting position can be held when the stopper is positioned at the restriction position such that the stopper covers, in a plan view from the mounting direction, a center-of-gravity position of the relay. a socket body including a mounting part on which a relay is to be mounted in a mounting direction; and a holding lever supported on the mounting part of the socket body and configured to hold the relay mounted at a mounting position of the mounting part, wherein the holding lever includes: a support extending from the mounting part of the socket body in a removing direction opposite to the mounting direction; and a stopper provided on an end part of the support distal to the socket body in the removing direction and configured to restrict movement of the relay, positioned at the mounting position, in the removing direction, a support extending from the mounting part of the socket body in a removing direction opposite to the mounting direction; and a stopper provided on an end part of the support distal to the socket body in the removing direction and configured to restrict movement of the relay, positioned at the mounting position, in the removing direction, the stopper is provided on the support and configured to move between a restriction position and a restriction release position, wherein at the restriction position, the stopper restricts movement of the relay, positioned at the mounting position, in the removing direction from the mounting part, and wherein at the restriction release position, the stopper releases the restriction of the movement of the relay, positioned at the mounting position, in the removing direction from the mounting part, and the holding lever is supported on the mounting part and configured to move between a retreat position and a holding position, wherein at the retreat position, when the stopper is positioned at the restriction release position, a relay can be mounted at the mounting position of the mounting part and the relay mounted at mounting position can be removed, and wherein at the holding position, the relay positioned at the mounting position can be held when the stopper is positioned at the restriction position such that the stopper covers, in a plan view from the mounting direction, a center-of-gravity position of the relay.