To settle a problem regarding the case where only such a device as a door open/close lock device is available, though the application of a pushbutton type lock device to a toy case is desired, but it cannot be adopted, due to a complicated structure and high production cost as bottlenecks.

When a pushbutton 30 on a case body is pushed, the feed tooth 22 of a cylinder 14 is moved forward by one pitch via a tumbler 15, and a cutout 20 on the cylinder 14 gives a gradual circumferential motion. Furthermore, when the cutout 20 stops at the prescribed position, a hook piece formed on the reverse side of a case is coupled to the cutout 20, and kept in an engaged state. Then, the pushbutton 30 is pushed to turn the cylinder 14, thereby providing a locked state.