A focus detection apparatus comprising a focus detection sensor formed by arranging a plurality of pairs of line sensors, each pair of line sensors receiving light beams that have passed through different pupil areas of an imaging lens configured to form an object image, a sensitivity setting unit configured to set a sensitivity for each pair of the plurality of pairs of line sensors, a selection unit configured to select line sensors of the pair of line sensors, whose signals are to be used for focus detection calculation, and a calculation unit configured to perform the focus detection calculation using the signals of the line sensors selected by the selection unit.