A plurality of illumination elements obliquely irradiating an inspection target region in irradiation directions different from each other and equiangularly spaced around an image capturing part in a state where each of a low-angle, intermediate-angle, and high-angle illumination parts has a different irradiation angle are sequentially turned on and off. An image of the image captured region is captured every time each of the plurality of illumination elements is turned on. A determination image generation part specifies an inspection-excluded region based on at least one of maximum luminance image data and minimum luminance image data of three types of captured image data each corresponding to an irradiation angle of each illumination part and generates determination image data for the image captured region other than the inspection-excluded region. A defect determination part determines existence of a defect based on the determination image data.