In an image processing device capable of collectively estimating an object based upon results of plural times of inspection, regions (1(1)) and (1(2)) to be photographed are defined on opposite end portions of an object (w). When an image of the left end portion of the object (w) is captured in response to a first trigger, the image processing device acquires corresponding image data, and the length (x1) of a projection extending in the x-direction at the left end of the object (w). When an image of the right end portion of the object (2) is next captured in response to a second trigger, the image processing device captures corresponding image data and measures the length (x2) of a projection extending in the x-direction at the right end of the work (w). Thereafter, the device finds the sum (x1+x2) of the lengths (x1, x2) inside, and outputs a result externally.