Provided is an AD converter including a first AD converting unit in which pixel columns of a pixel array are divided into at least two groups, and that compares a first ramp signal and a first pixel signal output from a first group of the pixel columns and performs AD conversion on the first pixel signal; and a second AD converting unit that compares a second ramp signal and a second pixel signal output from a second group of the pixel columns and performs AD conversion on the second pixel signal, in which the first ramp signal is a signal of which a level is decreased with a constant slope over time in a D-phase period for detecting a signal level of a pixel signal, and the second ramp signal is a signal of which a level is increased with a constant slope over time in the D-phase period.