An interpolation processing method for performing interpolation processing of image data obtained by photoelectrically converting an object image using interpolation data, includes a first step of estimating object information, a second step of generating first input image data based on the object information, a third step of generating first transformation data from the first input image data to the image data, a fourth step of generating second transformation data from the first input image data to interpolated image data after the interpolation processing, and a fifth step of generating the interpolation data using the first and second transformation data.