To provide a heater device capable of uniformly heating a heating object in the longitudinal direction of a bar-shaped heater.

This heater device 10 comprises the bar-shaped heater 20 comprising a heating wire 24 generating heat by power distribution, a cover member 30 covering at least a part of the bar-shaped heater 20 provided with a plurality of airflow adjustment windows 32 respectively having various opening patterns along the longitudinal direction of the bar-shaped heater 20, and an air distributing device 50 for distributing the airflow toward the bar-shaped heater 20 through openings 34 of the airflow adjustment windows 32, and a flow of the airflow F is adjusted to be increased and decreased along the longitudinal direction by changing the opening patterns of the airflow adjustment windows 32 in several ways.