PURPOSE: To contrive preventing the flow-out of resin holding the other part in a resin liquid by radiating ultraviolet rays while rotating an element coil by exposing a part where the irradiation with the ultraviolet rays is required from the surface of the resin liquid after impregnating a low-viscosity ultraviolet ray hardening type resin in the element coil.

CONSTITUTION: An ultraviolet ray hardening type resin 2 is impregnated in an element coil 1 housed in a container 3 for treatment by such impregnation means as vacuum pressurizing. The element coil 1 is raised from the surface of the resin liquid or the surface of the liquid is dropped only to the extent wherein the irradiation with an ultraviolet rays irradiation equipment 4 is possible and the ultraviolet rays are radiated to form a resin gel 5 on the surface of the element coil 1. The resin gel 5 is continuously formed by rotating the element coil 1 but the rotation is done intermittently or continuously within the irradiation range of the ultraviolet ray irradiation equipment 4. During the process of irradiation, the element coil 1 is gradually exposed from the surface of the resin liquid or of the surface of the liquid is dropped to the same extent and simultaneously, the ultraviolet ray irradiation equipment 4 is moved to the opposite direction from the direction of the rotation of the element coil 1.