PURPOSE: To simplify the fixing and releasing operations of lock by a method in which an operation handle to open or close a tight mechanism and a coupling bolt by an interlocking part is provided on the outside of a door panel, and concurrent switching operation is made by the one operation handle.

CONSTITUTION: A tight mechanism 26, a coupling bolt 27, and an interlocker 28 for coupling different clamping objects are provided in a door panel 3, and an operation handle 29 to open or close these through the interlocker 28 is provided to the outside of the panel 3. A case 34, a slide frame 35 to receive the action of the interlocker 28 reciprocally supported on the case 34, and a tight piece 33 for come-in and out operation supported on a cam mechanism 36 are provided. The piece 33 and the frame 35 are concurrently moved on the final end of stroke of the slide frame 35 and the panel 3 and a clamping object are pulled to each other by the tight mechanism 26. The door panels 3 can thus be exactly closed.