A refrigerant liquid level measuring device that measures a refrigerant liquid level in a short period is provided. A catalyst layer is formed at fixed intervals on the surface of the strip-form polymer electrolyte membrane in the lengthwise direction thereof, and conveyance holes are formed in series at fixed intervals on the two side portions thereof. The coils are serially coupled sequentially from front to back and back to front wherein the coupling of the coils is through a plated through hole in the flexible circuit board.