To improve the durability of a combustion case of a hot air heating device and prevent deformation or cracks due to the distortion of thermal contraction.

A combustion case cover 5 is attached to the outside of the side surface of the combustion case 2 so that the temperature difference between the inner surface of the combustion case 2 near a flame and an outer surface coming into contact with outside air 4 can be reduced, or speed at which the combustion case is cooled from high temperature to ordinatry temperature when the combustion operation is switched off can be lowered to achieve the above described purpose.