The present invention discloses a focus detection device capable of reading a plurality of focus detection outputs in parallel. As an exemplary structure, the focus detection device includes a focus detection sensor having a plurality of output terminals for outputting, in parallel, analog data corresponding to focus states of multiple points in the field of a viewfinder, a multiplexer for arranging and outputting, in chronological order, the analog data output in parallel from the plurality of output terminals of the focus detection sensor, and an A/D converter for converting, to digital data, the analog data arranged in chronological order through and output from the multiplexer.