To provide a pulse width modulation control device capable of reducing the number of signal transmission lines for transferring a gate signal.

A pulse width modulation control device is provided with a parallel - series conversion circuit 12 for converting a plurality of gate signals that are subjected to pulse width modulation generated based on an output instruction to a series data signal, signal transmission lines C1 and C2 for transmitting a series gate signal that is outputted from the parallel - series conversion circuit 12 and a synchronizing clock signal that is synchronized to it, a series - parallel conversion circuit 14 for converting a series gate signal that is transmitted via the signal transmission line to a parallel gate signal that is synchronized to the clock signal, and organization circuits 15 and 16 for organizing a parallel gate signal that is outputted from the series - parallel conversion circuit 14 to a gate signal for each switching element.