PURPOSE: To lengthen the life of a concrete pile as well as to facilitate removing clamping bolt by a method in which the head of PC steel is prevented from projecting to the upside of an anchorage plate and also a tap hole is adquately formed.

CONSTITUTION: The fixing plate 1 of an octagonal PC steel head is provided with the throttled projection of the lower hole of a tap hole 2 and the throttled projection 5 of the anchorage hole 4 of the PC steel head. A deep drawing process is applied to the lower hole of the tap hole 2 and the throttled projection 7 of a through hole 6 is formed. The lower hole and through hole 6 of the tap hole 2 are formed, the upside surrounding of the fixing seat of the PC steel head is framed 8, and the tap hole 2 is subjected to a tapping process.