A heating device includes: a heater; and a power distribution controller. The heater heats a predetermined heating target. The power distribution controller controls supply of AC power to the heater. The power distribution controller performs power distribution to the heater in units of AC half wave, and controls the power supply to the heater in accordance with power distribution control patterns respectively corresponding to a first time period as a power distribution start period, a third time period as a power distribution stop period, and a second time period between the first time period and the third time period.