A belt examination system includes a defect candidate detecting processor that detects a candidate for a belt defect that is an abnormal portion of an intermediate transfer belt of an image forming apparatus from a belt image that is an image of the intermediate transfer belt, the defect candidate detecting processor executes a background pattern reduction step to reduce a texture-pattern like background noise present in the belt image and detects the candidate based on the belt image generated during the background pattern reduction step, and the background pattern reduction step is to replace, in the belt image, a color value within a specific range of color values not including a lowest color value of the belt defect with a specific color value within the specific range.