現行『日本國憲法』是日本敗戰而被美國強制接受的憲法，其內容與戰前的明治憲法有根本性的差異，但其制定過程是依照舊憲法的修憲程序，因此雖有制憲的事實但卻是修憲的形式。另一方面，目前這部日本憲法連條文都是當時美國占領當局所擬定，因此跟台灣的情形一樣是「外來憲法」，因此從出現的那天起就不斷地有反對它的聲音，但施行迄今已超過七十幾年，卻一次也就是一個字都沒有更動過，因此許多日本政治家包括現任首相安倍晉三都說希望能施行「新憲」，但可能採取的做法還是修憲的形式。從『明治憲法』到『日本國憲法』的實質絕對是制憲，而排除「外來憲法」做出自己的憲法也絕對是制憲，因爲兩者在內容與意義上都是截然不同而沒有連續性的。但是日本進行憲法改革都基於現實考量，而在形式上採用舊憲法的修憲程序。這種情形對區隔制憲與修憲的理論有何影響？如果重視實際而不拘泥形式，那麼是否只要內容符合需求，連憲法名稱不用更動也可以？本文只在依據「憲法制定權力」的基礎，從日本實際與形式的交錯的「制憲」，探討區隔制憲與修憲的理論。

The current Constitution of Japan is a constitution that was accepted from the US occupation authorities after United States defeated Japan in WWⅡ. Its content is fundamentally different from the Meiji Constitution before the war, but its formulation process is in accordance with the constitutional amendment procedure of the old constitution. On the other hand, the current Japanese Constitution has been drafted by the General Headquarters (GHQ) at the time, so it is the ＂foreign constitution＂ just as in the case of Taiwan. The essence of the constitution from the Meiji constitution to the Japanese Constitution is absolutely constitutional, and the exclusion of the ＂foreign constitution＂ to make its own constitution is absolutely constitutional, because the two are completely different in content and meaning without continuity. If you pay attention to the actual and not formal form, then as long as the content meets the needs, even the constitutional name does not need to be changed. This article is only based on the ＂constitution power.＂ The foundation is to explore the theory of constitutionalism and constitutional revision in which Japan is actually intertwined with the form.