There is provided a solid-state image sensor including a pixel array unit in which pixels are arrayed, the pixel including a photodiode converting an optical signal into an electrical signal, and a readout unit which reads out an analog image signal from the pixel to a signal line and processes the read out analog pixel signal in a unit of column. The readout unit includes a ΔΣ modulator which has a function to convert the analog pixel signal in to a digital signal, and an amplifier which is arranged on an input side of the ΔΣ modulator and amplifies the analog pixel signal read out to the signal line using a set gain to input the signal to the ΔΣ modulator.