PURPOSE: To realize the best driving by displaying both the rotating speed and suction pressure of an engine at the same position simultaneously with light emission colors of illuminating segments.

CONSTITUTION: Diodes Da (Da1WDan) of the segments S (S1WSn) are controlled by a transistor (TR) Ta with the output signal of a monostable multivibrator (MM)6 to turn off when the suction pressure of the engine is high and the output signal of the MM6 is at 'H' and illuminate when the suction pressure of the engine is low and the output signal of the MM6 is at 'L'. On the other hand, diodes Db (Db1WDbn) of the segments S are controlled by a TRTb with the output signal of an inverting circuit 7 to turn off when the suction pressure of the engine is low and illuminate when high. Thus, the diodes Da and Db turn on and off according to the suction pressure of the engine so that one turns off when the other turns on; and the diodes Da and Db emit light of different colors, so the light emission color of the all segments S which illuminate varies and the best driving is realized.