As for reasons supporting that Tokyo is regarded the Capital of Japan, two are generally given: the Emperor who is prescribed by Japanese Constitution as "the symbol of Japan and the symbol of Japanese people's integration" is permanently stationed and the Imperial Palace is located in Tokyo, and also the highest organs of the three powers ruled by Japanese Constitution such as the Diet (legislature), the prime minister's official residence and central government ministries and agencies (administration) and the Supreme Court (administration of justice) are located in Tokyo (they are especially concentrated in Chiyoda Ward).
しかし東京都が首都とみなされる理由としては、日本国憲法で「日本国の象徴であり日本国民統合の象徴」と規定される天皇が常在し、皇居が東京都に所在すること、同じく憲法で国会（立法府）、首相官邸や中央省庁（行政府）、最高裁判所（司法府）という三権の最高機関のいずれもが東京都（中でも千代田区）に所在することが挙げられる。