To prevent deterioration in the viscosity of glycerin when fuel is supplied.

A body 30 of an oil filling-hot water supply unit 4 includes an outer cylinder and an inner cylinder 32 provided in the outer cylinder 31. An automatic oil filling unit 40 is installed below the body. An oil filling pipe 33 connected to the automatic oil filling unit 40 is provided on the bottom of the inner cylinder 32. A hot water supply tank 34 which is fixed to the inner face of the outer cylinder 31 by a support member at a certain interval and in which hot water is filled around the inner cylinder 32 is formed in the inner cylinder 32. The inside of the inner cylinder 32 serves as an oil supply tank 35. A hot water pipe 38 is extended from a lower stage of the outer cylinder 31 and connected to an intermediate stage of the outer cylinder 31 through the inside of a body 1 of a combustion part 2. Hot water in the hot water supply tank 34 is heated by the combustion part 2, and the hot water heats glycerin in the oil supply tank 35. The glycerin is supplied to the combustion part 2 by the automatic oil filling unit 40.