An image processing apparatus includes an optical system having distortion aberration characteristics for expanding a central part and compressing a peripheral part of an image plane; an image sensor for photodetecting an optical image via the optical system, converting the optical image to image signals, and outputting the image signals; a correction coefficient output circuit for outputting a correction coefficient for correcting the image signal with respect to a defect pixel of the image sensor, wherein the correction coefficient is determined based on the distortion aberration characteristics and a position of a peripheral pixel around the defect pixel; and a correction value computing circuit for computing a correction value with respect to the image signal of the defect pixel, based on the image signal of the peripheral pixel and the correction coefficient.