To provide a locking device for compactly constituting the whole device while maintaining a cipher operable structure with a simple structure.

This locking device 3 has one digit part 30, and a plurality of piece parts 34 are arranged in this digit part, and a plurality of push-button switches 32 are arranged in the longitudinal direction of this digit part 30. This locking device 3 fixes the respective pierce parts 34 to the digit part so that an opening inclined part of the piece parts 34 is opposed to a position opposed to its tip part 32e when operating the respective push-button switches 32. When successively pushing down the push-button switches 32, the respective push-button switches 32 move the digit part 30 in the opening direction (the left direction) by pushing the respective piece parts 34. Then, the device is unlocked by releasing engagement of a second wedge part 46 and a first key part 38. Thus, when using this locking device, the whole device can be compactly constituted more than a conventional locking device having a plurality of parallel digit parts while maintaining a cipher operable mechanical simple structure.