An object counting system includes an acquisition means for acquiring information of an estimation area which is a partial area of an image with which partial area a predetermined condition related to objects to be counted shown in the image are associated, the estimation area being a unit of area for estimating the number of the objects to be counted, a setting means for setting the estimation area in the image in such a manner that the estimation area indicated by the acquired information of the estimation area includes the objects to be counted which are not included in the objects to be counted in a different estimation area, and which satisfy the predetermined condition, an estimation means for estimating, in each estimation area, the number of the objects to be counted shown in the estimation area set in the image, and a computation means for computing a density of the objects to be counted in an area where predetermined areas in the estimation area are overlapped using the number of the objects to be counted that has been estimated in each estimation area.