PURPOSE: To perform the optimal control irrespectively of the fuel component by controlling a fuel control valve for performing feedback control under normal operation of LPG engine on the basis of the stored level of the actuator position for operating the valve when performing feedback control under open-loop control.

CONSTITUTION: When controlling a fuel supply valve for LPG engine, feedback control 102 is performed if the answer of the feedback area 101 is YES under normal engine operation to drive 103 a valve step motor while to calculate 106 the time average step position if the answers of the learning area 104 and predetermined time elapse 105 are YES and upon elapse of predetermined time 107, a fuel component correction factor is calculated 108 from the average step position to rewrite RAM109. While under open-loop control, the target step is calculated 111 to correct 112 with the rewritten value 109 in RAM thus to drive 113 a step motor.