A conducting wire end portion joining method is a method for conductively joining together end portions of conducting wires each covered with an insulation coating. The conducting wire end portion joining method includes: adjoining end portions of two winding wires, and bringing the end portions of the conducting wires of the two winding wires into contact with a conductive coating material stored in an insulating cap having a property of shrinking when heated; and shrinking the insulating cap by heating to fix the shrunken insulating cap around the insulation coatings of the end portions of the two winding wires, and joining together the end portions of the two winding wires by conductively connecting the conducting wires of the two winding wires via the hardened conductive coating material.