PURPOSE: To enhance painting quality after drying by avoiding the generation of an air stream over the zones in a painting drying oven in the operation of the painting drying oven wherein the discharged air from a plurality of the zones in the oven is subjected to incineration treatment in a combustion apparatus and the fresh air distributed and supplied to the zones in the oven is heated by the heat exchange with the discharged combustion gas from the combustion apparatus.

CONSTITUTION: With respect to the zones 3 in an oven, the amounts of discharged air and the supply amounts of heated fresh air are fixed to almost equal amounts Qa, Qb, Qc and the temp. Ta of heated fresh air is set so that the quantity of heat applied to the respective zones 3 in the oven by the supply of heated fresh air always becomes insufficient with respect to the necessary quantities Wa, Wb, Wc of heat of the zones 3 in the oven and the outputs of the radiation heating devices 12 arranged to the respective zones 3 in the oven are adjusted so that the insufficient quantities of the necessary quantities Wa, Wb, Wc of heat are compensated by the radiation heating devices 12 with respect to the heat load fluctuations of the respective zones 3 in the oven.