High-resolution AD conversion can be performed at a high speed in a CMOS image sensor in which column-parallel ADCs are mounted. In a CMOS image sensor 10 in which column-parallel ADCs are mounted, reference voltages Vref1 to Vref4 having slopes with different gradients and a reference voltage Vref5 are used. Additionally, a comparison circuit 32 that compares an output voltage Vx of a unit pixel 11 with any one of the reference voltages Vref1 to Vref4, and a comparison circuit 33 that compares the one of the reference voltages Vref1 to Vref4 with the reference voltage Vref5 are included in a column processing circuit 15. High-resolution AD conversion is performed at a high speed by respective operations of the comparison circuits 32 and 33 and an up/down counter 34.