To provide an auxiliary lock device which is compactly and simply constituted and which prevents a dead space from being formed in the installation of equipment and the like.

A front guard is rotatably and slidably connected to a lock base, fixed to a front portion of a fixed frame body, by means of a pivot passing through a slot-like bearing hole of a connecting arm portion. A stopper is fitted into a part of a guide groove of the front guard and an expanding slot of the lock base in such a manner as to be movable in a width direction. An inner wall surface of the expanding slot is provided with a locking retainer portion which is engaged with/disengaged from a locking protrusion of the stopper. A driving protrusion of a camshaft interlocked with a rotor of a lock unit abuts on a passive slope portion of a camshaft hole of the stopper, and the stopper is moved and urged toward an inner wall surface of the guide grove by a spring member. In a locked state in which the locking protrusion and the locking retainer portion are engaged with each other, a front guard-side abutting portion abuts on a lock base-side portion to undergo abutment, so as to inhibit the turning of the front guard with respect to the lock base.