A superconductive coil includes a plurality of pancake coils made of superconductive wires which each have cooling surface and on each of which first and second fine grooves are respectively formed in different directions wherein the first fine grooves are formed in a step of preparing the superconductive wires and the second fine channels are formed on the pancake coils which is constructed by winding said superconductive wires having the first fine grooves in the form of a pancake.
