PURPOSE: To obtain a circuit in which a program can be immediately and rapidly executed by a processor, and plural memories can be simultaneously checked by checking the memories with a hardware without any operation of software by the processor.

CONSTITUTION: At the time of power supply or in an arbitrary timing, a switching control signal 101 is outputted from a checking part 1, and a switching part 2 is switched to inside connection. Then, the checking part 1 writes arbitrary inside data 109 for checking in a memory cell 3 by an inside writing signal 107 with an inside address 108 and also writes the data in a register (1) 4. Next, the checking part 1 reads the data of the memory cell 3 by an inside reading signal 106 from the same address as that at the time of writing the data in the memory cell 3, and preserves the data in a register (2) 5 as the reading data 108. The checking part 1 operates one series of operation from the start address of the memory cell 3 of the final address, ends the checking operation at the time of reaching the final address, and switches the switching part 2 to an outside input connecting state.