Apparatus for detecting the presence of a flame using a UV tube which can be supplied with a DC voltage via an operating resistor, at least two UV tubes which are arranged in this manner and have substantially the same field of vision being provided, and the two UV tubes being able to be switched on and off in succession with a gap of a predefined time within a predetermined interval of time via a controller, with the result that the UV tubes are switched on for a predeterminable period of time, the number of pulses obtained from each UV tube being able to be recorded and compared with one another, the anode of the respective UV tube being able to be connected to earth potential between the operations of switching the UV tubes off and on in order to draw ionization in the discharge area.