To provide a dot pattern reading technology for efficiently irradiating a dot pattern by a few light sources while preventing highlight.

This mouse having the dot pattern reading unit optically reading a dot pattern formed on a medium face is provided with an irradiation light source radiating the medium face formed with the dot pattern with light, a lens for making reflection light from the dot pattern incident on a camera, and a mouse main body which has an aperture part serving as entrance/exit for the irradiation light from the irradiation light source and the reflection light from the medium face and is brought into contact with the medium face. In the mouse main body, an extension part 41a extended from the mouse main body and formed of transparent resin is arranged on the bottom face abutting on the medium face. A hole part 41b allowing visual recognition of the medium face is formed in the extension part 41a, and through the hole part 41b, the dot pattern on the medium face is irradiated with light, and the dot pattern is read.

COPYRIGHT: (C)2008,JPO&INPIT