A heat treatment apparatus and control method enabling the apparatus to settle down an internal temperature of a treating vessel to a target temperature accurately and quickly. The heat treatment apparatus includes a furnace body with a heater on an inner circumferential surface thereof, the treating vessel disposed inside the furnace body, a cooling medium supply blower and cooling medium release blower each connected to the furnace body, and a temperature sensor provided inside the treating vessel. A signal from the temperature sensor is sent to a heater output computing unit and blower output computing unit included in a controller. The heater output computing unit determines a heater output level based on a heater output numerical model and the signal from the temperature sensor. The blower output computing unit determines a blower output level based on a blower output numerical model and the signal from the temperature sensor.