Provided is an image processing device for blacking out a scattered ray region without losing the imaging object information in the scattered ray region of a radiograph. An image processing device (56) for executing a concentration correction process on an obtained radiograph by using a recording plate (52) capable of accumulating radiographic information, wherein the radiograph contains a valid image region (72) corresponding to a region in which the recording plate (52) is present, and an invalid image region (74) corresponding to the region in which the recording plate (52) is not present. Furthermore, the image processing device (56) is provided with: a region-to-be-corrected identi fication unit (82) for identifying a pre-set range of regions (94) within the valid image region (72) that are adjacent to the invalid image region (74) as to-be-corrected regions (90) and concentration correction units (84, 120) for correcting the concentration level of pixels in the to-be-corrected regions (90) by removing the concentration level trend in the to-be-corrected regions (90) that become present when moving from the valid image region (72) side toward the invalid image region (74) side.
