When electric discharging occurs inside a gas insulated apparatus in which sulfur hexafluoride is filled, hydrogen-fluoride gas is generated, which abrades a part formed of glass fiber reinforced plastics included in the apparatus. Previously, resin for preventing the abrasion has been coated on the surface of the part; however, a problem has occurred that the coating film peels off. Organic fiber woven cloth woven using organic fiber such as aramid fiber or the like having hydrogen fluoride resistance and mechanical toughness is wrapped around the surface of glass fiber reinforced plastics, and thermosetting resin is wettably impregnated into weave patterns of the organic fiber woven cloth and then heat cured; thereby, an abrasion-preventing protection layer that does not peel off is formed.