A connector mateable along a predetermined direction with a mating connector comprising a locked portion, the connector comprising two power terminals, at least one signal terminal, a mated-state detection member and a holding mechanism, wherein: the holding mechanism comprises a reference surface, a plurality of insulating portions and an insulating external wall; the insulating portions include two insulating portions for the power terminals, and at least one insulating portion for the signal terminal; each of the insulating portions projects from the reference surface by a first predetermined length in the predetermined direction; the insulating external wall projects beyond the reference surface in the predetermined direction and surrounds the insulating portions in a plane perpendicular to the predetermined direction; each of the power terminals is held by the holding mechanism and extends along the predetermined direction; the power terminals have ends, respectively, and the ends of the power terminals are accommodated in the insulating portions for the power terminals, respectively; the at least one signal terminal is held by the holding mechanism and extends along the predetermined direction; the at least one signal terminal has an end which is accommodated in the at least one insulating portion for the signal terminal; the mated-state detection member is held by the holding mechanism and is movable between a projecting position and a receding position in the predetermined direction; when the mated-state detection member is positioned at the projecting position, the mated-state detection member projects from the reference surface by a second predetermined length which is shorter than the first predetermined length; and when the connector is mated with the mating connector, the mated-state detection member is pushed by the mating connector and is moved to the receding position, characterized in that: the holding mechanism comprises a lock member and a lock maintenance member other than the lock member; the lock member has a lock portion and is selectively positionable at a lock position or an unlock position; when the lock member is positioned at the lock position, the lock portion locks the locked portion to lock a mated state of the connector with the mating connector; when the lock member is positioned at the unlock position, the connector is removable from the mating connector; the lock maintenance member is selectively takable a maintenance state or a permission state; when the lock maintenance member is under the maintenance state, the lock maintenance member restricts a movement of the lock member from the lock position toward the unlock position; when the lock maintenance member is under the permission state, the lock maintenance member permits the movement of the lock member from the lock position toward the unlock position; and when the mated-state detection member is positioned at the projecting position, the mated-state detection member prevents the lock maintenance member from taking the maintenance state; and when the mated-state detection member is positioned at the receding position, the mated-state detection member permits the lock maintenance member to take the maintenance state.