Abstract: An image restriction method includes: acquiring image data by a capturing part, the image data being obtained by capturing a space in which a monitoring target object is disposed; acquiring capturing position data indicating a capturing position of the capturing part in the space; acquiring shape information indicating a three-dimensional shape of the monitoring target object; specifying a disposition position of the monitoring target object in the space; specifying a shape of the monitoring target object disposed at the disposition position, based on the capturing position data, the shape information, and the disposition position, and specifying a region of the monitoring target object in an image of the acquired image data, based on a result obtained by the specifying the shape; performing a masking process on a region other than the specified region of the monitoring target object, in the image of the acquired image data; and outputting mask-processed image data.