PURPOSE: To enable an economical heating operation to be attained by a method wherein a heater inputting, value capable of getting an amount of radiation suitable for a human body at a location spaced apart by a distance is calculated from data about a room temperature and the distance.

CONSTITUTION: A distance sensing part 12 converts an output of an ultrasonic wave sensor 3 into a digital signal acting as an inputting data of a distance L ranging from a heater 2 to a human body. A room temperature sensing part 13 converts an output from a temperature sensor 7 into a digital signal acting as an input data of a room temperature. A table for converting the amount of radiation suitable for a selected human body into a heater inputting value in response to a room temperature for every spaced-apart distance between the heater 2 and the human body is stored in advance in a heater input table 15. In this way, it becomes possible to perform a comfortable heating operation suitable for the human body more under a heater capability control responding to the distance from the heater as well as the room temperature.