A liquid level detector may comprise an arm attached to a float, a rotator fixed to the arm, a magnet fixed to the rotator, a supporter rotatably supporting the rotator. The supporter may comprise a body housing a magnetic sensor and opposing the magnet with a clearance, a supporting portion disposed along a rotation direction of the arm on an outer circumference side of the magnet and projecting from the body toward the rotator, and a flange portion projecting from the supporting portion along an outer circumference direction at a position spaced from the body in a rotational axial direction of the arm. The rotator may comprise an engaging portion slidably disposed relative to the flange portion along the rotation direction of the arm and engaging the flange portion so as to regulate a motion of the arm in the rotational axial direction.