To provide an indoor heater for warming the inside of a toilet booth by controlling heater output by predicting and detecting an indoor temperature and a temperature of a blowout part, and preventing scorching of a floor and a wall by preventing the blowout part of hot air from becoming a high temperature.

This indoor heater is composed of an air blowing fan 3a of a hot air heating unit 3 and a heater 3b arranged on the downstream side, and blows out the hot air from a blowout port 3c in a hot air heating operation state of driving the fan 3a, and supplying electric power to the heater 3b, and controls output of the heater and the fan on the basis of output of a blowout temperature detecting means for predicting the temperature of the blowout part of the hot air.