PURPOSE: To set a dead time of a control signal for sampling control within a prescribed time by synchronizing the sampling timing with the external control signal.

CONSTITUTION: A sampling control circuit 2a is provided with a control signal entry means 21 receiving an external control signal and with a sampling timing synchronization means 22 generating a pulse to reset a count of a counter circuit of a timer 25 every time the control signal is received via the entry means 21. A microcomputer 23 implements arithmetic processing based on the control signal in a succeeding sampling timing generated from a sampling timing generating means 25 to set a dead time of the control signal for sampling control within a prescribed time.