PURPOSE: To uniformly heat and bake a painting material painted to an object to be worked, at a desired temperature, by forming a V-groove ring on a pair of rollers of a carrying tool, installing a discoid object to be worked, and shifting the object to be worked, in a drying furnace, rotating it by friction force.

CONSTITUTION: In a head part box 12 of a carrying tool 6, a pair of roller shafts 91 are installed at the same height, and to the projecting end of this roller shaft 91, a pair of rollers 131, 132 on which a V-groove ring 141 is formed are stuck. To the V-groove ring 141 of these rollers 131, 132, the inside circumferential surface or the outside circumferential surface of a hollow discoid object to be worked 15 is intalled so as to be bridged. When the rollers 131, 132 are rotated, friction force works on both the inside circumferential surface of the object to be worked 15, and the V-groove ring 141, and the object to be worked 15 rotates on the vertical surface. In this state, when the carrying tool 6 is shifted into a drying furnace 1, a painting film of the surface of the object to be worked 15 is uniformly baked, even if a temperature distribution of a panel heater 2 is ununiform.