To provide a coil for electromagnetic expansion which realizes easy positioning of a work and highly accurate electromagnetic expansion work.

A coil for electromagnetic expansion consists of a shaft part 2 around which a conductive wire 4 is coiled and a flange part 3 provided on a proximal end part of the shaft part. A positioning part 6 with which the work 5 is to be fitted is formed on the end part on the flange part 3 side of the shaft part 2. A forming die 7 which is disposed outside the work 5 to form an outer surface of the work is fixed to the flange part 3. When performing electromagnetic expansion, the shaft part 2 is inserted in the work 5. Since the end portion of the work is fitted with the positioning part 6, the work 5 is disposed at a predetermined distance from the shaft part 2.