A focus detection device includes: a defocus information detection unit that detects phase difference information indicating a phase difference manifested by a pair of images formed with a pair of light fluxes having passed through different areas of a photographic optical system and detects defocus information based upon the phase difference information; and a correction unit that executes correction for correcting the defocus information, detected by the defocus information detection unit, in correspondence to a predetermined direction extending between a first direction that orthogonally intersects an optical axis of the photographic optical system and radially extends from the optical axis and a second direction that orthogonally intersects the first direction.