A thermotherapy device with a reclining surface (6) for a patient and with two radiant heaters (3, 4) directed towards the reclining surface (6) and with a control unit (5), which is set up to control the heat output of each of the radiant heaters (3, 4). The reclining surface (6) includes structure for pivoting about an axis of rotation (12) at right angles to a body axis (11) of the patient. An angle or slope sensor (13) detects the deviation of the position of the reclining surface (6) from the horizontal plane. The control unit (5) is connected to the angle or slope sensor and adapts the heat output of each of the first radiant heater and of the second radiant heater (4) as a function of the detected measured value of the slope such that the heat output of each heater differs by a predetermined factor and the heat output of each heater is equal when the reclining surface is in the horizontal position.
