An image pickup apparatus includes a pixel generating a signal by photoelectric conversion, a comparator comparing the signal based on the pixel with a reference signal varied with time, a counter performing counting until the comparator outputs a signal indicating that a relationship in magnitude between the signal based on the pixel and the reference signal is reversed, and a control unit. The comparator includes a first amplifier receiving the reference signal at a first input portion and the signal based on the pixel at a second input portion to compare the signal based on the pixel with the reference signal. The control unit sets a bandwidth of the comparator to a first bandwidth when the reference signal varies at a first rate of change and to a second bandwidth when the reference signal varies at a second rate of change.