A determination system includes an imaging data acquisition device that captures an image of a printed surface of a printed product to acquire imaging data of the captured image, and a determination device that determines, based on the imaging data, a printing method used to produce the printed surface of the printed product for which the image is captured by the imaging data acquisition device. The determination device selects a plurality of determination areas included in the captured image, acquires determination data based on a line-segment image included in each of the determination areas, compares the acquired determination data between two determination areas, and acquires, based on a result of the comparison, a determination value for determining a printing method used to produce the printed surface of the printed product, and determines, based on the determination value, a printing method used to produce the printed surface of the printed product.