Provided is a molded body with a hollow portion comprising tetrafluoroethylene and perfluoro(alkyl vinyl ether) copolymer, which is obtained by heat treating a molded body with a hollow portion obtained by melt molding tetrafluoroethylene and perfluoro(alkyl vinyl ether) copolymer having a melt flow rate of 0.1 to 100 g/10 min when measured with a load of 5 kg and a measurement temperature of 372±0.1° C. in accordance with ASTM D1238. The heat treatment is carried out at a temperature from 130° C. below the melting point of the copolymer to the melting point of the copolymer. The molded body exhibits excellent blister resistance when utilized in contact with harsh chemicals and under harsh operating conditions.