To provide a connecting device which is easy to assemble and which an accessary such as a chain is easily attached to and detached from.

The device comprises a movable member and a fixed member. The movable member is provided with a hook on the side of a distal end and a pair of side wall parts on the right and left on the side of a proximal end facing each other, and has projecting parts for a shaft which project toward the center at a pair of the side wall parts and which oppose each other with a narrow space therebetween. The fixed member has a pawl part where the hook is hooked formed on the side of its distal end, and the fixed member is provided with an insertion piece part to be inserted to a gap between a pair of side wall parts on the side of its proximal end. A hole for fitting the projecting parts for the shaft part from both of the right and left sides nearly at the center of the insertion piece part and a pair of boss parts along the outer periphery of the hole are formed. The projecting parts for the shaft part fitted to the boss become pivots to connect the movable member in a pivotable manner, and the movable member is biased in a closing direction of hooking the hook to the pawl part by a spring provided at a pivotally attaching place.