WATER LEVEL DETECTION DEVICE

PROBLEM TO BE SOLVED: To provide a water level detection device which can effectively prevent detection omission caused by deposition of floating matters with simple structure.SOLUTION: The water level detection device comprises: an optical fiber; a Faraday type proximity sensor for controlling intensity of light emitted to the optical fiber according to strength of magnetic field; a sensor case for housing the Faraday type proximity sensor; a float incorporating a magnet for changing the strength of the magnetic field at the Faraday type proximity sensor; and a guide part for regulating the ascent/descent direction of the float with ascending/descending of water level. The water level detection device comprises a positioning part for determining an installation state when the water level detection device is installed on an installation surface. When the water level detection device is installed on the installation surface according to the positioning part, distance from the installation surface to the float is smaller than distance from the installation surface to the guide part, that is, the guide part is not interposed between the installation surface and the float.