PURPOSE: To uniformly heat a resin raw material by sufficiently supplying hot air to a mold without blocking hot air by certainly removing the resin refuse falling to be bonded to a filter means each time when the resin raw material is heated from below to eliminate a removal impossible state due to the carbonization of resin refuse.

CONSTITUTION: A slush mold A having a resin raw material bonded to the molding surface a1 thereof is fed to the upper part of a hot air blowoff device 3 blowing off hot air upwardly by a feed device 59 so that the molding surface a1 is turned downwardly. A metal net is positioned between the slush mold A fed by the feed device 59 and the hot air blowoff device 3 so as to be movable between the upper part of the hot air blowoff device 3 and the lateral part thereof and, when the slush mold A passes through the upper part of the hot air blowoff device 3, the metal net receives the resin refuse falling from the molding surface al of the slush mold A and the resin refuse falling to the metal net to be bonded thereto is removed by the brush roll 63 provided on the lateral side of the hot air blowoff device 3.