To oscillate and output multiphased triangular waves with a designed waveform shape, wave crest value, and phase relationship. This multiphased triangular wave oscillating circuit has two triangular wave generating circuits 10A and 10B for generating two phased triangular waves A and B with phases opposite each other, a middle point potential fixing element 20 that always fixes the middle point potential of the output voltage A and B of the two triangular wave generating circuits 10A and 10B at a fixed value, and a mode switching element 30 that instantly switches the output voltage generation mode (up-slope waveform mode/down-slope waveform mode) in the two triangular wave generating circuits 10A and 10B at a preset reference wave crest value level.