To easily and inexpensively obtain a triangular wave voltage signal synchronized with AC power.

This triangular wave voltage generating device 1, for generating the triangular wave voltage signal synchronized with the AC power 2, is provided with a 1st absolute value circuit 11 for taking the absolute value of a sine wave voltage signal obtained from the AC power 2, a 2nd absolute value circuit 12 for taking the absolute value of a cosine wave voltage signal obtained from the AC power 2, and a differential amplifier circuit 20 for generating a triangular wave voltage signal, by taking the difference between the output of the circuit 11 and the output of the circuit 12 and amplifying the difference.