1. A component presence/absence judging apparatus for judging whether or not a component is mounted at a predetermined place on a board after a component mounting operation that mounts the component on the board, the apparatus comprising: an image pickup device for relatively moving the board and a camera to pick up an image of a predetermined portion on the board where the component is to be mounted; and circuitry configured to: acquire ante-mounting color information from an ante-mounting image that the camera picks up at a predetermined portion on an ante-mounting board before mounting the component at the predetermined place; acquire post-mounting color information from a post-mounting image that the camera picks up at a predetermined portion on a post-mounting board after mounting the component at the predetermined place; determine an inspection area by identifying a section having a large difference between the ante-mounting color information and the post-mounting color information, and by identifying a section image having a large difference between brightness information on at least two lights at each of the section images of the ante-mounting image and brightness information on at least two lights at each of the section images of the post-mounting image that respectively correspond to section images of the ante-mounting image; store, in a memory, for each predetermined portion, the inspection area, the ante-mounting color information, and the post-mounting color information in the inspection area; acquire post-mounting operation color information from the inspection area on a post-mounting operation image that the camera picks up at a predetermined portion on an inspection board after the component mounting operation; and judge whether or not the component is mounted at a predetermined place on the inspection board, by comparing the post-mounting operation color information with the ante-mounting color information and the post-mounting color information.