PURPOSE: To fully draw out potential added values and consequently obtain a heating device with better operational conveniences by a constitution wherein the detection levels of desired sensors are selectively displayed on the display part such as fluorescent display tubes and the like by means of a keying input means such as operating keys and the like operated by a user.

CONSTITUTION: Firstly, a room temperature display key 26, which assigns an air intake part thermistor 10 to monitor the temperature by converting the signal level monitored by the thermistor 10 into the Celsius scale, is provided. When the room temperature display key 26 is inputted, the room temperature of the moment is displayed on a numerical display part 20a. Similarly, when a humidity display key 27 is inputted, the relative humidity of the moment at an air exhaust part 7 is displayed on the numerical display part 20a. Further, when an oven temperature display key 28 is inputted, the temperature in a box is displayed in the Celsius scale. Furthermore, when an exhauat air temperature display key 29 is inputted, the temperature at the air exhaust part 7 is displayed in the Celsius scale.