An image sensor includes: first pixels, each of which receives a pair of light fluxes and outputs a pair of first analog signals; an A/D conversion unit that converts each of pairs of first analog signals to a pair of first digital signals; a digital adder unit that generates digital sum signals each by adding together the pair of first digital signals among pairs of first digital signals; a first output unit that outputs pairs of first digital signals to an external recipient; and a second output unit that outputs the digital sum signals to an external recipient.