To surely hold both receiving seat bodies abutted on both sides of a door body to the lock body by strong holding force, and improve it in strength.

One side receiving seat body 14 abutted on one side face of a door body in the direction of thickness another side receiving seat body 18 abutted on another side face of the door body in the direction of the thickness, and a lock body 7 having an engaging hole 9 and a latch 12 protruding from and retreating in the end of the door stopper of the door body. One side receiving seat body 14 has one side engaging projection body 16 inserted in the engaging hole 9 of the lock body 7 from one side opening end of the insertion hole penetrating the door body. The other side receiving seat body 18 is inserted in the engaging hole 9 of the lock body 7 from the other side opening end of the insertion hole of the door body and has the other side engaging projection body 20 engaged with one side engaging projection body 16 at the time of insertion of the engaging hole 0. Both of the side engaging projection bodies 16, 20 have engaging parts 16c, 20c mutually meshed and engaged with the insertion hole 9 of the lock body 7, and the engaging parts 16c, 20c are composed of uneven meshing parts 16d, 20d.