In the hydrogen remaining sensor of the present invention, the hydrogen remaining sensor is arranged in a space in which the hydrogen is absorbed/released by the main hydrogen storage alloy, and is equipped with the vessel-like sensor main body in which the sensor hydrogen storage alloy is filled and through which the hydrogen is moved. Also, the easy-to-deform portion in which the strain is caused easily due to the hydrogen absorption/release of the sensor hydrogen storage alloy is provided to a part of the sensor main body, and the strain gauge for measuring the strain of the easy-to-deform portion is provided. As a result, according to the hydrogen remaining sensor of the present invention can contribute to sense precisely a remaining amount of hydrogen in the main hydrogen storage alloy.