1. A component presence/absence judging apparatus for judging whether or not a components is mounted at a predetermined place on a board after a component mounting operation which mounts the component on the board, the apparatus comprising: an image pickup device for relatively moving the board and a camera to pickup an image of a predetermined portion on the board where the component is to be mounted; ante-mounting color information acquisition means for acquiring ante-mounting color information from an ante-mounting image which the camera picks up at the predetermined portion on an ante-mounting board before mounting the component at the predetermined place thereon; post-mounting color information acquisition means for acquiring post-mounting color information from a post-mounting image which the camera picks up at the predetermined portion on a post-mounting board after mounting the component at the predetermined place thereon; inspection area determination means for determining an inspection area by identifying a section having a large difference between the ante-mounting color information and the post-mounting color information; storage means for storing, for each predetermined portion, the inspection area and the ante-mounting color information and the post-mounting color information in the inspection area; post-mounting operation color information acquisition means for acquiring post-mounting operation color information from the inspection area on a post-mounting operation image which the camera picks up at the predetermined portion on an inspection board after a component mounting operation which mounts the component at the predetermined place thereon; and judgment means for judging whether or not the component is mounted at the 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.