In the early stage of excavation there was a presumption that it was a gunga (regional public office) of Natori County along with a kokufu of Mutsu Province or a stockade of a castle whose name does not appear in documents, but at present the accepted theory is that the stage II kanga was the kokufu of Mutsu Province before Taga-jo Castle was.
発掘当初は、陸奥国府説と並んで、名取郡の郡衙や、文献に名が出ない城柵ではないかとする推測もあったが、現在ではII期官衙を多賀城以前の陸奥国府とするのが定説である。