PURPOSE: To make easier the breaking work of concrete structure by providing a breaking means into a hollow tube formed when removing the PC steel member of a concrete structure into which a prestress is introduced.

CONSTITUTION: A prestress introducing device is attached to vertical shaft of the ground 1. The prestress introducing device consists of a PC steel member 3, a coupler 4 connecting with the PC steel member 3, and a hollow tube 5. Concrete is placed into the shaft and hardened, and then the PC steel member 3 is dragged upwards by a clamper 12 in such a way as to introduce prestress into the concrete structure 9. On the other hand, when breaking the structure 9, the PC steel member 3 is turned toward opposite direction to that for clamping it and removed from the hollow tube 5. Then, a breaking means, e.g., explosive, etc., is attached into the hollow tube 5 to break the structure 9.