The present invention provides a liquid surface detection device 1 in which corrosion is restrained even when liquid having conductivity is used so that a longer lifespan is achieved, including a liquid surface detection sensor 2 that outputs a signal indicating a variation in liquid level as a variation in resistance value by the sliding movement of a contact point 2a on an electrode connected to a resistor 2b, and a control unit 4 that controls supply and stops a supply of electric power to the liquid surface detection sensor 2 at predetermined intervals, in which a vehicle state determination unit that determines a state of a vehicle is provided and the control unit 4 controls the duration to stop the supply of electric power to the liquid surface detection sensor 2 when the vehicle state determination unit determines that the vehicle is in a traveling state.