A method is provided, for manufacturing a stator for a rotary electric machine by shrink-fitting an outer cylinder to a core assembly where a cage-shaped wound coil is assembled with segment cores. The assembly is inserted into the outer cylinder having a diameter increased by thermal expansion caused by the heat from a heating unit, while the outer diameter of the assembly is being reduced by permitting the assembly to pass through a tapered guide unit. The guide unit has a portion whose diameter is larger than an outer diameter of the assembly, and a portion whose diameter is larger than an inner diameter of the outer cylinder and smaller than an inner diameter of the cylinder in the thermally expanded state, and a tapered through hole vertically passing through the guide unit. Thus, the size of the assembly is radially reduced, with a uniform diameter being obtained throughout the assembly.