Abstract: A method for detecting a molten metal surface level in a casting mold, comprises inserting an electrode in a slag constituting a layer under a flux floating on the surface of the molten metal, detecting a change of electric resistance due to a temperature gradient of the place at which the electrode is inserted, displacing the electrode to bring the detected value to be always constant within a range of from 5 to 50 .OMEGA., and measuring the degree of the displacement of the electrode thereby detecting the surface level of the molten level. An apparatus for carrying out the method is also disclosed.