An image processing device including a storing unit storing the position of a focus detecting pixel of an image-capturing sensor containing plural pixels having spectroscopic characterizations corresponding to respective plural color components with the focus detecting pixel, a pixel interpolating unit generating an interpolation pixel value of the focus detecting pixel by using pixel values of pixels neighboring to the focus detecting pixel, neighborhood-pixel estimating unit calculating an estimation pixel value corresponding to a pixel value when the pixels neighboring to the focus detecting pixel have the same spectroscopic characterization as the focus detecting pixel, a high-frequency component calculating unit calculating a high frequency component of the image by using a pixel value of the focus detecting pixel and the estimation pixel value, and a high frequency component adding unit adding the interpolation pixel value with the high frequency component to calculate a pixel value of the focus detecting pixel.