PURPOSE: To prevent the absorption of moisture by winding by coating the internal surface of insulating cylinder at the inside of winding with a moisture- proof insulating material and by hermetically sealing the external surface of insulating cylinder at the outside and the edge of winding with an insulating film covered thereon in view of holding and supporting them.

CONSTITUTION: The insulating cylinders 7, 8 provided at the inside and outside of a coil 1 are fixed by providing a coil holding means 5 and a supporting means 6 to the axial end of coil 1 through a spacer 4. The internal surface of insulating cylinder 7 is coated with an insulating material 10 having particular moisture resistant characteristic and the external circumference of insulating cylinder 8 and both holding means 5 and supporting means 6 are respectively covered with an insulating films 11, 12 having excellent moisture resistant characteristic. Thereby, the insulating cylinders 7, 8 are hermetically sealed and the coil 1 is transported while it is shielded from the atmospheric condition. When the coil in such a structure is transported and reassembled, the coil 1 has less chance of absorbing moisture and therefore re-drying process in the installation site can be omitted and simultaneously highly reliable coil of induction apparatus can be obtained.