山幸的海宮訪問譚是《古事記》《日本書紀》中所收錄的神話故事，該故事與日本史上之初代天皇－神武天皇的誕生有関，是一則連繫日本神代以及天皇時代的重要神話。山幸的海宮訪問譚是海幸山幸神話的後半部，其前半部為兄弟釣針相爭的故事（釣針喪失譚）。然而前半和後半的故事，就故事的發展上而言，並無必然的連結性，前後兩部分為不同系統的故事。為何不同系統的兩則故事會連結在一起？這代表甚麼意義？本論文從這些問題出發，企圖以日本神話中的山幸海宮訪問譚為主要的考察對象，透過其與環太平洋區域的類似故事之比較分析，以解析山幸海宮訪問譚的構造、特色以及《古事記》《日本書紀》之編撰意圖。 透過本論文的考察，可以指出以下兩點結論。第一點是：山幸的海宮訪問譚是在「釣針喪失譚」的基礎上，加入「兄弟相爭」的這個母題，並多加強調。同時，又在「海宮訪問的異界婚」的要素上，再加入宇宙三界之結合以及地上最大君王之誕生的物語。第二點是：山幸海宮訪問譚和環太平洋區域中的海宮訪問譚相比之下，相當具有特色，而該特色的背後，有著大和朝廷和阿曇氏的強烈動機和願望。

"Yamasachi’s Underwater Tour" is a fairy tale collected in "Kojiki" and "Nihonnsyoki". It doesn’t only refer to the birth of the first Japanese emperor, Zinnmu, but also connects Japanese god and emperor eras. The story is the second part of the myth about Umisachi and Yamasachi. The first part is about the story of brothers’ fighting for a fishhook. However, there isn’t bound connection between the two stories. They could be separated and independent. Why are two independent stories linked together? What does that mean? This paper will start from these questions, targeting the tale of "Yamasachi’s Underwater Tour", comparing similar tales around the Pacific Rim, and attempts to find out the tale’s structure and characteristics and the editing intention of "Kojiki"and "Nihonnsyoki" We can make two conclusions by this paper. The first, "Yamasachi’s Underwater Tour" is based on "Fishhook Fighting", and adds a motif of brothers’ competition to emphasize. Furthermore, the story is composed of the element of "underwater exotic wedding", Yamasachi’s tour and the birth of the greatest emperor on earth. The second, "Yamasachi’s Underwater Tour" has a distinctive feature from similar stories around the Pacific Rim. Behind it, we can find the strong motive and wish of Yamato imperial court and Azumisi.