A frequency-stabilized laser device comprises an actuator arranged to vary the cavity length; an actuator driver arranged to apply a voltage to the actuator for changing displacement; a temperature detector arranged to detect the temperature on the cavity; a temperature adjuster arranged to heat or cool the cavity; a cavity temperature controller arranged to control the temperature adjuster based on a previously given instruction temperature and the temperature on the cavity detected at the temperature detector; and an instruction temperature corrector arranged to correct the instruction temperature given to the cavity temperature controller such that the voltage applied to the actuator remains almost constant.