An image pickup device, comprises: a pixel configured to output a signal based on a light reception amount; and an AD conversion unit. The AD conversion unit includes: an amplifier circuit configured to amplify a signal that is output from the pixel; a comparator circuit including an output node for outputting a comparison result signal generated by using an output signal from the amplifier circuit and a ramp signal; a memory configured to hold a digital value corresponding to the output signal, based on a result of the comparator circuit; a gain switching circuit configured to switch a gain of the amplifier circuit; and a ramp signal switching circuit configured to switch a slope of the ramp signal. The gain switching circuit and the ramp signal switching circuit are electrically connected to the output node.