To obtain satisfactory signal characteristics by a simpler constitution.

An A/D conversion circuit comprises: a lamp generation unit which generates a gradient lamp signal to be referred to when an analog signal is converted to a digital signal; a comparator which compares the analog signal with the lamp signal and outputs the result of the comparison; and a counter which outputs a count value based on the result of the comparison by the comparator. The lamp generation unit is constituted by arranging plural capacitor elements in parallel. This technique can be applied to a CMOS image sensor, for example.