An automatic power control (APC) circuit applicable to controlling a laser generation module including a laser generator for generating laser and a photosensor for outputting a detection result corresponding to the power of the laser, includes: a comparator, coupled to the photosensor and biased by a first voltage level, for comparing the detection result and a reference signal to generate a comparison result; a level shifter, coupled the comparator, for shifting an intermediate voltage level controlled by the comparison result to generate a control voltage; and a driver, coupled to the level shifter and the laser generator, for driving the laser generator according to the control voltage and a second voltage level.