Abstract: An insulating roll is provided which is constructed with a roll body formed of a plurality of inorganic material-derived discs laminated with each other and positioned axially of and around a metal conduit, and a heat-resistant metal tube disposed integrally over an outer periphery of the roll body. A tubular cover formed by spray coating a ceramic material on the heat-resistant metal tube, or a sleeve made of sintered ceramic material may be disposed, where desired, in place of the heat-resistant metal tube. This roll has low thermal conductivity and high impact strength without involving feduction of the surface temperature of a material being heat treated in a furnace, or reduced ambient temperature in the furnace during heat treatment.