To provide a heater capable of using heat stored in a building frame part as residual heat and carrying out an energy-saving operation.

The heater includes: a floor heater body 2 (heater body) for heating an indoor space 6 (heating object zone); and a control means 4 to control operations of the floor heater body 2. The heater can operate a stored heat use mode of using heat stored in a building frame part of the indoor space 6. In an operation of the stored heat use mode, the control means 4 controls operations of the floor heater body 2 by considering the heat stored in the building frame part during a heating operation. Also, in addition to the stored heat use mode, preferably, it is possible to set a normal mode of not using the heat stored in the building frame part. In an operation of the normal mode, the control means 4 controls operations of the floor heater body 2 without considering the heat stored in the building frame part during a heating operation.