PURPOSE: To prolong the service life of an electrode by constituting the electrode for dipping in a molten metal, with SiC material.

CONSTITUTION: The electrodes 3, 4 for detecting the standard and high levels respectively and penetrating a lid 1a of a furnace 1 used for measuring liquid level of a high purity molten aluminum 2, are vertically movable by a lift 6. A fixed electrode 5 is penetrated to a peripheral wall 1b of the furnace 1, and respective electrodes 3, 4, 5 are formed of rod or rod-shaped material made of SiC. The lower end of the electrode 3 is positioned at the place lower than that of the electrode 4. The electrode 3 or 4 is brought into contact with the liquid level of the bath 2, and the current flowing between said electrode and the electrode 5 is detected to obtain the liquid level height. In this way, the contamination due to the melting of the electrodes 3, 4, 5 into the melt 2 can be prevented.