Abstract: A molded joint boot obtained by using a highly hard and highly elastic thermoplastic polyester elastomer as the molding material. The molded boot is formed into the shape of a conical bellows having a major-diameter portion connected to a minor-diameter portion by a tapered wave-like portion. Along the direction from the major-diameter portion to the minor-diameter portion, the ratio of the outside diameter of the crest portion on the minor-diameter side of a given wave to the outside diameter of the immediately-preceding trough portion of the same wave is confined within the range of about 1.08 to about 1.40. The subject molded boot is processed by injection molding, and the thermoplastic polyester elastomer employed as the molding material is above about 70 kg/cm.sup.2 in tensile yield strength, above about 30% in tensile yield elongation, and within the range of about 430 kg/cm.sup.2 to about 1700 kg/cm.sup.2 in tensile elasticity modulus.