To solve the problem of a conventional cold shrink tube which is liable to generate a crack at an inner periphery of both end faces as a maximum stress position when the tube is widened.

A mold composed of a core 1 and a main die 2 is assembled so as not to form a seam at the inner peripheral position A of both end faces of the cold shrink tube. By the above, the mold is constructed so as not to generate any crack at the inner periphery of both end faces of the cold shrink tube as a maximum stress position, when the tube is widened.