A portable heat transfer apparatus comprises a mixture forming/supply device for producing a mixture of fuel gas and air, a heating unit including a heat collection casing, and a burner installed in the casing and formed with a combustion chamber having a flat surface. The burner includes a large number of holes formed on an upstream side thereof to extend up to the flat surface to allow the mixture injected into the chamber therethrough to combust in the chamber, and a porous solid radiant-heat conversion component to partly convert heat energy of exhaust gas from the combustion in the chamber into radiant heat energy. The conversion component defines at least a surface region of the chamber located opposite to a flame front produced close to the flat surface. The apparatus includes a heat-driven pump joined to the casing and receiving heat generated by the combustion, through the heat collection casing.