An elastic tube expanding method comprising the steps of fitting an elastic tube (6) around a free end portion of an expander (1) which is formed at least at its outer surface portion out of a coagulated material of a low melting point substance, and which has a tapering portion (4) the diameter of which is substantially equal to or smaller than the inner diameter of the elastic tube (6) to be expanded, and then passing the elastic tube (6) along a low friction melting surface of the coagulated material, whereby the elastic tube (6) is expanded.
