To continuously catch a melted state of a raw material and hence accurately judge melting time by collecting waste gas exhausted from an electric furnace, measuring concentration of a predetermined component in the waste gas, and judging that the raw material is melted when concentration of the predermined component becomes a predetermined threshold.

A melting judgment apparatus 1 brings waste gas exhausted from an electric furnace 10 into reaction and combustion with air, and collects combustion gas with a sample probe 3, continuously measures concentration of a component of the waste gas that changes in response to a melted state of a stock material, and decides that the raw material is melted with judgement means 6 when the component concentration of the waste gas becomes a predetermined threshold or less set by set means 5, and displays a judgement result on display means 7. For this, melting judgment accuracy of the melting judgment apparatus 1 is higher than a prior art method with observation in a furnace, and hence inconvenience such as non-melting of a raw material and excess supply of electric power can be prevented.