To provide a pulse signal generator which makes it possible to calculate and set the duty ratio and/or 8-period of a modulation pulse each time while minimizing increase in a processing load.

Using an A/D conversion value of a current detector 6 generated according to a modulation pulse of this round, a CPU starts calculating the duty ratio/period of a modulation pulse of the next round (timing of (3)). A prescribed time t is set as a time exceeding the maximum calculation time of the CPU calculating the duty ratio and period. The CPU can terminate the calculation processing before the prescribed time t elapses after a count CNT reaches a count threshold Ct.