To reduce variation of a detection range in a liquid level detector provided with a float.

This liquid level detector 10 is provided with: the float 11 floating on a liquid face in a liquid storage tank 20; an arm 12 attached to the float 11 to convert a vertical motion of the float 11 into a rotational motion around a rotary shaft Z as the center; and rotation angle detectors 15, 16 for detecting a rotation angle of the arm 12. The rotation angle detectors 15, 16 outputs at least one of a lower limit value in the position where the float 11 abuts to a bottom face 21 of the liquid storage tank 2, and an upper limit value in the position where the float 11 abuts on an upper face 22 of the liquid storage tank 2. The variation of the detection range is thereby reduced in the liquid level detector 10.