A solid state imaging device includes a plurality of pixels arranged in a matrix, a plurality of vertical signal lines VL arranged to correspond to columns of the pixels, respectively, such that each of them is connected to the pixels in each column and a column amplifier including a plurality of amplifiers AP. Each of the amplifiers AP includes a current source MOS transistor T1, an amplifying MOS transistor T2 for amplifying an image signal and a cascode MOS transistor T3 which is cascode-connected to the amplifying MOS transistor and outputs an amplified image signal between the cascode MOS transistor T3 and the current source MOS transistor T1. Gate terminals of the cascode MOS transistors T3 of the amplifiers AP are connected to each other.