MOBILE OBJECT LOCK MECHANISM

A lock mechanism (for example, a small object storage device for a vehicle) includes a base (for example, a housing), a mobile member, and a lock device. The lock device includes a lock portion; a knob; a return spring; an elongate hole for movably supporting at least one end portion of a rotational axis along a moving direction (for example, a sliding direction) of the mobile member; an urging device (for example, the return spring also serving as the urging device) for urging one end portion of the rotational axis toward a position of a front side of the elongate hole; and a rotation blocking portion for blocking a rotation of the knob when the one end portion of the rotational axis moves toward a deep side of the elongate hole against an urging force of the urging device (for example, the return spring also serving as the urging device).