An image processing apparatus includes an image acquirer configured to acquire an image, a function acquirer configured to acquire a plurality of optical transfer functions relating to an optical system, a function reviser configured to revise the plurality of optical transfer functions based on information relating to an image pickup element, a converter configured to convert the plurality of optical transfer functions revised by the function reviser into a plurality of point spread functions, and an image restorer configured to perform restoration processing on the image by using the plurality of point spread functions.