A solid-state imaging device includes: a plurality of pixels which are arranged in a matrix; a sequential scanning device that selects each row of pixels; and an analog-to-digital conversion unit having a first analog-to-digital converter that is connected to a vertical signal line to which a pixel signal is supplied from the pixel and performs a first bit-length analog-to-digital conversion on an output signal from the vertical signal line or a pixel output signal obtained by sampling the output signal, and a second analog-to-digital converter that, when the first analog-to-digital converter completes the conversion operation, subtracts an analog signal corresponding to the first bit-length from the pixel output signal and then performs a second bit-length analog-to-digital conversion.