To provide a heating apparatus for a greenhouse, capable of heating the interior of the greenhouse using methane gas obtained by fermenting an agricultural waste, etc., as a fuel and utilizing the resultant fermentation residue as an organic liquid fertilizer and improving the safety and environmental pollution resistance without using a fossil fuel at all.

This heating apparatus for a greenhouse is capable of using methane gas produced by fermenting an agricultural waste such as a compost, excreta of dairy farming cattle or pig and poultry farming and household leftover rice as a fermentation fuel in a fermentation fuel chamber 22 as a fuel, supplying and circulating heated hot water heated with a heater capable of generating heat with a platinum or a palladium catalyst 40 through the interior of the greenhouse, heating the interior of the greenhouse, taking out an organic liquid fertilizer which is the fermentation residue and reutilizing the liquid fertilizer.