A color determination unit determines color information of a light-emitting body of an input device. A transmitter unit communicates the determined color information to the input device. A recording unit records a history of the color information determined by the color determination unit. A color candidate determination unit determines one or more candidates of emitted color of the light-emitting body, using the color information recorded in the recording unit. An acknowledging unit acknowledges from the user a command to determine a candidate of emitted light, and the color determination unit determines the color information of the light-emitting body accordingly.