PURPOSE: To obtain a pile with a simple edge structure by interlocking a coupler nut having screws in and out of one end thereof and having an interlocking projection to the other end with the head of a PC steel bar, and using it as a bolt hole for connecting ends after introducing prestress.

CONSTITUTION: A coupler nut 1 having a female screw to screw with a bolt 7, a male screw to screw with an end plate 10 and a conical interlocking projection is interlocked with the head 9 of a PC steel bar 8. Then, a jack introducing prestress is fixed with a fixing bolt 12, and prestress is introduced. After that, the bolt 12 is removed to use it as a fixing screw for a end connection bolt 7, and it is used both as the PC steel bar and connection bolt. According to the constitution, a prestressed concrete pipe with a simple edge structure can be obtained.