To make flexibility and creep resistance at a high temperature excellent by coupling polyester-based copolymer of a specified composition and polyether of a specified rate which is constituted of repeating units expressed by a specific formula by an isocyanate component of a specified rate in which specific formulas are made constituent units.

This tubular molding body is formed by block copolymer of polyester-based copolymer which is constituted of the repeating of short chain and long chain polyester components expressed by a formula I and a formula II and has short chain polyester components 50 to 95 wt.% and long chain polyester components 50 to 5 wt.% and polyether constituted of repeating units expressed by a formula III. Polyester-based copolymer and polyether are coupled by an isocyanate component C in which a formula IV or a general formula V are made constituent units and the tubular forming body is made of ester- based elastomer containing polyether 50 to 500 pts.wt. and the isocyanate component 10 to 100 pts.wt. for polyester-based copolymer 100 pts.wt.