PURPOSE: To make fitting strength of a handle great by making a wall of an apparatus of a part fitting over a connecting part of a handle body sufficiently thick, by a method wherin the wall part of heated parison which is to be fitted over the connecting part is colled before fitting-up.

CONSTITUTION: Since a part 11 becomes hard to extend by colling the part 11 which is to be fitted over a connecting part 31 of a handle body 3 of parrison 1 where the whole is heated to a molding temperature and is in a softened state before fitting-up of the part 11. Therfore, even when the part 11 is fittted over the connecting part 31 off the handle body by blow molding, the part 11 is not thinned and a bottle with a handle having great fitting strength is obtained. The handle body 3 is fitted beforehand to an established recessed part 21 of a blow mold 2 and the connecting part 31 is projected within a through a mold surface of the blow mold. when the parison 1 is stretched in an axial direction by a stretching rod 5 and stretched in a diametral direction by pressurizing gas, though the parioson 1 is extended as shown by a chain line with two dots 12, the part 11 which is to be fitted over is molded without a wall 4 of an apparatus on the circumference of the connecting part 31 is being extended extremely until the part 11 is left bhind as it is kept thick and fitting-over can be made to perform.