When making a potential of a floating node 0V at the time of nonselection, electrons leak from the floating node to a photodiode and noise is generated. A MOS type solid-state imaging device comprised of unit pixels 10, each having a photodiode 11, a transfer transistor 12 for transferring a signal of this photodiode 11 to a floating node N11, an amplifier transistor 13 for outputting a signal of the floating node N11 to a vertical signal line 22, and a reset transistor 14 for resetting the floating node N11, arranged in a matrix, wherein, as a buffer final stage 29 for driving a drain line 23, a buffer final stage having an inverter configuration formed by arranging a P-type MOS transistor on a ground side is used, thereby making the potential of the floating node N11 for example 0.5V at the time of nonselection and preventing electrons from leaking to the photodiode 11 through the transfer transistor 12.
A second source follower circuit of a reference voltage generator includes a transistor having the same characteristics as a first source follower circuit of a pixel. Accordingly, the second source follower circuit can generate a second reference voltage according to the change in characteristics of the first source follower circuit. A noise voltage switching circuit outputs a first voltage as a noise voltage to a pixel signal generator when the noise voltage is equal to or lower than the second reference voltage. In a reset state, the noise voltage and the second reference voltage always have a predetermined voltage difference. Therefore, deterioration in image quality can be prevented even when capturing a subject having high brightness. Since a trimming circuit or the like selecting any one of a plurality of reference voltages according to characteristics of a formed transistor becomes unnecessary, the cost of an imaging device can be reduced.
