PURPOSE: To improve efficiency in assembly and disassembly work, by taking a power conductor from each rotor conductor, laying the power conductor along a shaft, and using a commutator and a brush connected to the conductor and put at the both ends of the shaft.

CONSTITUTION: In a motor, a power line 25 taken from each conductor of a rotor 11 is laid along a shaft 10, and a commutator 21 is provided at both ends of the shaft 10. The conductor 25 and the commutator 21 are fixed. The commutator 21 has an outside diameter smaller than an inside diameter of a heat-insulating vacuum container 19, and a brush 22 in contact with the commutator 21 is put at an end thereof. In a step of assembling, after the rotor 11 is assembled, the power line 25 along the shaft 10 and the commutator 21 are fixed. A superconducting coil group 12 is put with the rotor 11 in between so that the brush 22 is put in contact with the commutator 21. In addition, in a step of dismantling, screws 29 and 30 are removed so that the brush 22 is pulled out from the shaft 10. After that, the heat-insulating vacuum container 19 is removed and the superconducting coil group 12 and can be taken out. Consequently, efficiency in assembly and disassembly work can be improved.