To provide an image processing method capable of creating image data where blood vessel pattern data of an organism is extracted with high precision.

A circumferential average brightness subtracting section 18 creates index data x showing the average value of the brightness shown by pixel data of a pixel around the pixel corresponding to the pixel data with respect to each pixel data constituting the image data S16 inputted from a vein sharpening section 16, and creates image data S18 by subtracting the index data x from each pixel data constituting the image data S16.