The invention relates to an apparatus for contactless temperature measurement of a melting charge located in a melting crucible 2 inside a melting furnace, in particular a furnace for precision casting, by means of a pyrometer 5 with an optical system 8 and at least one sensor 6 optically connected to said optical system 8, wherein said optical system 8 can be directed by means of a sight glass 18 onto at least one section of the melting crucible 2. In order to reduce soiling caused by smoke gas deposits on the sight glass, a tube is provided which is connected at its upper end to the sight glass 18, extends into a melting chamber 11 of the melting furnace and can be pointed in the direction of the melting crucible 2.