A focus detection apparatus includes:a first optical device for forming light distributions, associated with an object image, whose relative positional relationship chnages along a first direction in accordance with a focusing state of the objective lens;a second optical device for forming light distributions, associated with the object image, whose relative positional relationship changes along a second direction in accordance with the focusing state of the objective lens;a first sensing unit, having a plurality of photosensors, for forming an electrical signal associated with the focusing state of the objective lens in order to sense the light distributions formed by the first optical device; anda second sensing unit, having a plurality of photosensors, for forming an electrical signal associated with the focusing state of the objective lens in order to sense the light distribution formed by the second optical device.