To accurately detect theft of a product. An information processing apparatus (2000) acquires a reference image (13) in which a product exhibition location is imaged. In addition, the information processing apparatus (2000) acquires a comparison image (14), in which a product shelf is imaged at a time after the reference image (13) is imaged. Furthermore, the information processing apparatus (2000) computes the quantity of reduction in products inside a surveillance area (15) included in both the reference image (13) and the comparison image (14). Furthermore, the information processing apparatus (2000) outputs the warning in a case where the computed quantity of reduction is equal to or larger than the reference value.