To generate a ramp wave with reduced noise and reduced distortion of the waveform.

The waveform generator for generating a waveform comprises a ramp waveform generation section for generating a ramp wave of which the signal value linearly changes for a predetermined period of time, a rectangular wave generation section for generating a rectangular wave having a pulse width which is approximately the same as the predetermined period of time, a waveform addition section for performing addition of the ramp wave and the rectangular wave by approximately coinciding the timing at which the signal value starts to change in the ramp wave with the timing of the leading edge of the rectangular wave, and a low-pass filter for rejecting components having a predetermined frequency bandwidth from the waveform output by the waveform addition section.