Liquid surface sensor

A liquid surface sensor, comprising:

• a fastened body including a fastened main body that is fastened to a container storing a liquid, and an axle part that is a tubular shape and protrudes from the fastened main body;
• a float floating on the liquid, the float including an insertion hole into which the axle is inserted, the float assembled to the fastened body, the float being movable relative to the fastened body in a vertical direction in a case where the axle part is inserted into the through hole;
• a magnet part supported by the float, the magnet part generating a magnetic field;
• and
• a switch mechanism received in the axle part, the switch mechanism including a switch that is switched from an off state to an on state when being approached by the magnet part, a receiving part that receives the switch, an output part that is exposed from the receiving part toward a first direction of the axle part and to which a signal indicating the on state of the switch or the off state of the switch is transmitted, and a conductive film that is a film covering an outer surface of the receiving part and extending from the output part in a second direction opposite to the first direction and to which the signal transmitted to the output part is transmitted.