To provide a heating device capable of synchronously changing temperatures of heating targets to be heated by heating means in a configuration with a plurality of heating means.
When small step control for a heater 5A is completed, a temperature PV of the heater 5A usually reaches a target temperature TSV0(n) and large step control for a heater 5B starts in response to the above reach. On the other hand, next large step control for the heater 5A starts in response to the fulfillment of such conditions that the temperature PV of the heater 5B reaches a target temperature TSV1(n), an elapsed time (step time TS1) since the start of the large step control of the heater 5B is equal to or larger than a large step time T1ST, and an elapsed time (step time TS1) since the start of the large step control of the heater 5A is equal to or larger than the large step time T1ST.
