A focus detection apparatus comprises: an image sensing unit including photoelectric conversion elements for each microlens, with the microlenses being two-dimensionally arranged; a generation unit configured to generate a first signal pair having a first resolution from signals of a first area of the image sensing unit which corresponds to a predetermined focus detection area and generate a second signal pair having a second resolution lower than the first resolution from signals of a second area which corresponds to the predetermined focus detection area and is wider than the first area; a focus detection unit configured to perform phase difference focus detection processing based on at least one of the first and second signal pairs; and a recording image generation unit configured to generate a recording image from a signal output from the image sensing unit.