A focus detection apparatus includes first-type and second-type pixels and an image-formation-state detector. Each first-type pixel includes a photoelectric converter that receives light from an image-pickup optical system and first and second optical members arranged on an optical path from the optical system to the photoelectric converter and having different refractive indices, and outputs a first charge signal corresponding to an amount of light received by the photoelectric converter. Each second-type pixel includes the photoelectric converter and the first and second optical members arranged such that a positional relationship relative to the photoelectric converter differs from that in each first-type pixel, and outputs a second charge signal corresponding to an amount of light received by the photoelectric converter. The detector detects an image formation state of the image-pickup optical system on the basis of the first and second charge signals.