Liquid surface detecting apparatus

Provided is a thin liquid surface detecting apparatus wherein a thickness of a holder is suppressed. A liquid surface detecting apparatus is provided with: a holder rotatably held to a main body section; a magnet fixed to the holder; an arm, which connects the holder and a float floating on the liquid surface of a liquid, and which converts an up-and-down motion of the float into a rotation motion of the holder; and a magnetic detecting element, which is positioned at a rotation center portion of the holder, and is fixed to the main body section such that the magnetic detecting element intersects a magnetic flux of the magnet, and which detects a magnetic change generated with displacement of the magnet and converts the change into electrical signals. The liquid surface detecting apparatus detects the liquid surface on the basis of the electrical signals transmitted from the magnetic detecting element. The arm is fixed to the outside of the magnet of the holder, and a part of a cross-section in the direction perpendicular to the longitudinal direction of the arm fixed to the holder is positioned between an upper end and a lower end in the rotation axis direction of the magnet.