A drive control circuit 136 sends out pulse signals of various pulse signals so as to control light emission amounts and luminances of LEDs 26 by gradually increasing and decreasing the pulse width at predetermined cycles during predetermined periods on the basis of parameters supplied from an LED drive controller 132 that determine a first emission control processing period, a second emission control processing period, first to fourth slope durations and the like. The tones of the emitted colors obtained by a plurality of LEDs 26 are controlled by synchronizing periods of time of light emission control processings.