Abstract: Ariga Nagao, one of the first imperial scholars in the Meiji era, challenged Hozumi Yatsuka's theory of absolute monarchy. Their debates on the interpretation of the Meiji Constitution were regarded as the first controversy of the “Mikado Organ Thought”. As a theoretical contributor at the early stage, Ariga Nagao should have have been eligible to be included in the “Mikado Organ Thought” camp. But his Constitutional conception which concentrated on administrative rights is closer to the “Mikado Sovereignty Thought”. With the transformation of constitutional system in the early twentieth century, the contradictions between his theory and “Mikado Organ Thought” camp become increasingly acute. His theory on the constitutional theory of china was under attack by the Soejima Giichi, the representative scholar of “Mikado Organ Thought”. All in all, his constitutional theory was in a peculiar predicament.

Key words: Ariga Nagao, The “Mikado Organ Thought”, schools of constitutional theory, Hozumi Yatsuka, Soejima Giichi