A focus detection apparatus generates a focus evaluation value based on image data corresponding to a predetermined focus detection area. The focus detection apparatus includes a filter circuit, a reset circuit, a multiplication circuit, a coefficient generating circuit, and an integration circuit. The filter circuit filters image data to be input. The reset circuit generates a reset signal to reset the filter circuit. The multiplication circuit multiplies the image data by a predetermined coefficient and supplies the filter circuit with the image data multiplied by the coefficient as image data to be filtered after the reset circuit generates the reset signal. The coefficient generating circuit generates the coefficient. The integration circuit generates the focus evaluation value within the focus detection area based on an output of the filter circuit.