To acquire a method of construction, in which a shaft can be excavated safely and efficiently.

A drilling device 1 with a rotary table 15 capable of being rotated in a horizontal plane, a plurality of legs 5 lifting and bearing the rotary table 15 from a ground surface, a guide cell 30 being disposed in upright on the rotary table 15 and capable of being inclined so that the lower section of the guide cell 30 is directed towards the outside and central side of the rotary table 15, and a drill installed to the guide cell 30 vertically movably is used. A plurality of lower holes are bored downwards on a concentric circle while tuning the rotary table 15 at every fixed angle, and blasting or pressing is conducted by utilizing these lower holes and a bedrock is crushed.