A defect detection device for detecting a surface defect in an object, comprising: a light emission part capable of emitting light to an object from a first direction and a second direction different from said first direction; an image capturing part (3a, 3b, 3c) for acquiring an image of a target region of a surface of said object; an image capture controller for causing said image capturing part (3a, 3b, 3c) to acquire a first captured image while said object is being irradiated with light from said first direction, and causing said image capturing part (3a, 3b, 3c) to acquire a second captured image while said object is being irradiated with light from said second direction; and a defect acquisition part for acquiring, in said first captured image, a region whose lightness is lower than a lightness of a first reference image and lower than a value that satisfies a predetermined condition as a first dark region, acquiring, in said second captured image, a region whose lightness is higher than a lightness of a second reference image and higher than a value that satisfies a predetermined condition as a second light region, acquiring a region of overlap between said first dark region and said second light region as a defect candidate region, and acquiring an existence of a defect on the basis of said defect candidate region, said light emission part is capable of emitting light to said object from three or more directions that are different from one another, under control of said image capture controller, said image capturing part (3a, 3b, 3c) acquires three or more captured images by acquiring an image while said object is being irradiated with light from each of said three or more directions, and said defect acquisition part handles each of a plurality of images included in said three or more captured images as said first captured image, handles each of a plurality of images included in said three or more captured images as said second captured image, and uses a plurality of combinations of said first captured image and said second captured image to acquire said defect candidate region. a light emission part capable of emitting light to an object from a first direction and a second direction different from said first direction; an image capturing part (3a, 3b, 3c) for acquiring an image of a target region of a surface of said object; an image capture controller for causing said image capturing part (3a, 3b, 3c) to acquire a first captured image while said object is being irradiated with light from said first direction, and causing said image capturing part (3a, 3b, 3c) to acquire a second captured image while said object is being irradiated with light from said second direction; and a defect acquisition part for acquiring, in said first captured image, a region whose lightness is lower than a lightness of a first reference image and lower than a value that satisfies a predetermined condition as a first dark region, acquiring, in said second captured image, a region whose lightness is higher than a lightness of a second reference image and higher than a value that satisfies a predetermined condition as a second light region, acquiring a region of overlap between said first dark region and said second light region as a defect candidate region, and acquiring an existence of a defect on the basis of said defect candidate region, said light emission part is capable of emitting light to said object from three or more directions that are different from one another, under control of said image capture controller, said image capturing part (3a, 3b, 3c) acquires three or more captured images by acquiring an image while said object is being irradiated with light from each of said three or more directions, and said defect acquisition part handles each of a plurality of images included in said three or more captured images as said first captured image, handles each of a plurality of images included in said three or more captured images as said second captured image, and uses a plurality of combinations of said first captured image and said second captured image to acquire said defect candidate region.