To make it possible to surely regulate the moisture content of generated steam in a short time period and carry out moisture baking in addition to elimination of uneven baking for materials to be processed and controlling of uniform diffusion of heat.

An oven apparatus is composed by forming radiant heat flow channels of lower heat sources 4 so as to guide radiant heat through upper heat sources 3 to the upper side of a hot plate 2. In order not to produce excessive radiant heat from the upper heat sources 3 toward the materials W side to be processed on the hot plate 2, the oven apparatus is further composed of horizontal hanging plates 26 capable of being installed at an optional height through a gap at the top of a supporting frame 23 provided facing the installed upper heat sources 3 side so as to shield the radiant heat, and regulating plates 25 for heat shielding capable of enlarging or narrowing the gap on the lower edge side of the horizontal hanging plates 26 by making the regulating plates 25 for heat shielding freely movably fixable in the vertical direction on the lower end side of the horizontal hanging plates 26 so that joining of the radiant heat flux from the lower heat sources 4 with the radiant heat flux of the upper heat sources 3 is caused to produce convection and thereby improve the heat transmission to the materials W side to be processed on the hot plate 2.