由来
安房神社の創始は、今から2670年以上も前に遡り、神武天皇が初代の天皇として御即位になられた皇紀元年(西暦紀元前660年)と伝えられております。神武天皇の御命令を受けられた天富命(下の宮御祭神)は、肥沃な土地を求められ、最初は阿波国(現徳島県)に上陸、そこに麻や穀(カジ＝紙などの原料)を植えられ、開拓を進められました。
その後、天富命御一行は更に肥沃な土地を求めて、阿波国に住む忌部氏の一部を引き連れて海路黒潮に乗り、房総半島南端に上陸され、ここにも麻や穀を植えられました。 　この時、天富命は上陸地である布良浜の男神山・女神山という二つの山に、御自身の御先祖にあたる天太玉命と天比理刀咩命をお祭りされており、これが現在の安房神社の起源となります。
安房神社HPより引用
history
It is said that the founding of Awa Shrine dates back more than 2670 years, and is the first year of the imperial era (660 BC) when Emperor Jimmu became the first emperor. At the behest of Emperor Jimmu, Tentomi (the god of the lower shrine) was asked for fertile land, and first landed in Awa Province (currently Tokushima Prefecture), where hemp and grains (kaji = paper, etc.) Was planted and cultivated.
After that, in search of more fertile land, the Tentomi group took a part of Mr. Abe, who lives in Awa Province, on the Kuroshio Current and landed at the southern tip of the Boso Peninsula, where hemp and grains were also planted. It was. At this time, Awa Shrine is celebrating his own ancestors, Tenta Tamai and Tenbiri Swordsman, on two mountains, Otokoyama and Megamisan, on the landing site of Furahama. This is the origin of the current Awa Shrine.
Quoted from Awa Shrine HP