PURPOSE:To exactly and efficiently treat the head of a concrete pile already driven into the ground by using a pile head treater consisting of hollow bodies having at least one or more through holes formed from the upper part to the lower part. CONSTITUTION:The ground's surface A is excavated by a drilling bucket, etc., a casing tube B is driven into the hole, and an iron bar cage C is inserted into the tube B. A pile head treater 1 is inserted into the tube B, a fitting arm 6 whose one end is attached to a hollow body 1' is regulated in an extending or contracting manner, and a hook bolt 5a on the other end is hooked on any vertical bar C1 of the iron bar cage C on the periphery and tensely hung down by a trunbuckle 5c. A tremie tube (not illustrated) is inserted into the through hole 2 and raised while placing concrete to pack the concrete to near the upside of the hollow body 1'. The attachment and removal of the treater 1 and the placement of concrete can thus be performed easily and safely.