Provided is an AD converter that converts an input analog signal into a digital signal, comprising an integrator that sequentially integrates signal levels of the analog signal to obtain an integrated waveform, and outputs the integrated waveform; a digital converting section that detects, with prescribed units of temporal resolution, a transition timing, which is a timing at which a magnitude relationship between a signal level of the integrated waveform and a prescribed reference value transitions to a predetermined state; a feedback section that controls the signal level of the integrated waveform with a control period longer than a unit of temporal resolution, according to a result of the detection by the digital converting section; and a signal processing section that generates the digital signal based on the detection result by the digital converting section.