An image sensor including a pixel unit in which a plurality of pixels are arranged in a matrix, an A/D conversion circuit provided corresponding to each column of the matrix and configured to A/D-convert a pixel signal output from the pixel unit and output digital data corresponding to the pixel signal, a memory provided on each column, and a redundant data generation unit configured to generate redundant data based on a generating rule of an error correction code for the digital data, wherein the digital data and the redundant data are stored in the memory.