PURPOSE: To abate the extent of operating cost by erecting columns in the inner part of an abandoned mine for reinforcement, concreting an internal surface of the mine, and making a feed oil pipe out of a pit mouth creep along a shaft, while installing an oil feeding tank in the pit mouth.

CONSTITUTION: Columns 4 are erected in the inner part of an abandoned mine 5 for reinforcement, and an internal surface of the mine is concreted (2). Then, an oil feed pipe 3 out of a pit mouth 6 is made to creep up to the innermost part along a shaft, and a tank 1 provided with a motor so as to make oil feedable is installed in the pit mouth 6. With this constitution, an economical effect is securable in this way.