1. An image processing apparatus comprising: an obtaining unit configured to obtain mosaic image data by shooting a subject with use of a color image sensor in which five or more kinds of color filters are arranged in front of an image pickup device; a first interpolation unit configured to perform interpolation to color information of a high-definition color filter, in regard to the mosaic image data obtained by the obtaining unit; and a second interpolation unit configured to perform interpolation to color information of a low-definition color filter of which a peak wavelength in spectral transmittance is adjacent to that of the high-definition color filter, by using a result of the interpolation to the color information of the high-definition color filter by the first interpolation unit, wherein the mosaic image data is image data which has one color information for each pixel, and the five or more kinds of color filters include high-definition color filters and low-definition color filters.