The invention relates to an electric reflective plate device, which includes a rotary shaft, a reflective plate, a shaft set and a motor module. By the composition of above structure, the flip angle of the reflective plate may be adjusted by the motor module, and the previous flip angle may be memorized every time when the reflective plate is opened, so that the reflective plate may be quickly flipped to a desired angle, to thereby conveniently use a head-up display.