An image sensor includes: a readout circuit that reads out a signal to a signal line, the signal being generated by an electric charge resulting from a photoelectric conversion; a storage circuit including an analog/digital converter that converts a first voltage signal based on an electric current from a first power supply circuit into a digital signal and a first storage unit that stores the first voltage signal converted into a digital signal by the analog/digital converter; and a first electric current source that supplies the signal line with an electric current generated by the first voltage signal stored in the first storage unit.