The present invention provides a filter device and a transmission power control apparatus capable of outputting transmission power in the form of apparent loop gain commensurate with the present communication circumstances while maintaining settings provided as loop gain under transmission power control. The lowering in OLED brightness due to deterioration is reduced by causing the OLED to emit light while keeping constant the current flowing through the OLED instead of causing the OLED to emit light while keeping constant the OLED drive voltage. The pixel has a location on the GUI.