To provide a program executing device and a program executing method, which can reduce the memory capacity of a storage memory while preparing two programs with the same source program.

This program executing device 1 is constituted of a processor 2, a program memory, a storage memory 4, an address decoder 6, an address bus 11, a data bus 12, a read/write signal line 22, a start signal line 32, and an signal line 41 to be accessed. The address decoder 6 transmits a start signal to the storage memory 4 when a signal 302 to be accessed is '002' or '003'. Thus, the program executing device 1 converts two first address signals whose only signals to be accessed are different into the same second address signal.