The focus detection apparatus includes an image pickup part (101-107) including first and second pixels photoelectrically converting first and second images formed by light fluxes passing through different pupil area of an image-forming optical system to produce first and second image signals, a first signal processor (121) performing a first process to smooth the first and second image signals by using mutually different filters, a second signal processor (121) performing a second process to sharpen the first and second image signals by using mutually different filters. A calculating part (121) calculates a defocus amount by using the first and second image signals subjected to the first process when a contrast value is higher than a predetermined value, and calculates the defocus amount by using the first and second image signals subjected to the second process when the contrast value is lower than the predetermined value.