PURPOSE: To assure a reliable reset when a circuit board is inserted or removed and prevent an adverse effect to the main body device side by the malfunction of the circuit board when a hot line is inserted or removed by synthesizing a reset signal generated by the connection of a reset terminal and a reset signal sent from a reset signal generation section with a connecting means for use as the reset signal output of the circuit board.

CONSTITUTION: A reset signal generation section 15 has a power-on reset generation section 16 and a power-low reset generation section 19, and the power-on reset signal and the power-low reset signal are connected to a connecting means 20 via reset signal paths 17, 18 connected in common. The connecting means 20 is connected to a reset terminal 14d, the reset signal from the reset terminal 14d and the reset signal from the reset signal generation section 15 are synthesized to output a negative reset signal output 21. The output signal of the power-on reset generation section 16 is generated in the period (b) from the time when Vcc becomes the voltage V1 or above until the power-on reset signal is turned off, and the reset period (c) at the time of insertion is determined by the synthesis of the reset signals.