Hamaorisai has been started at middle of 19th century by Samukawa Shrine. Once Mikoshi of Samukawa Shrine dropped into the river and lost it. However, later on, people found their mikoshi at the Chigasaki Beach. After that, people started drop their mikoshi as Misogi, soul cleaning. Recently, people stop dropping their mikoshi at the beach, but still carry mikoshi in the beach. About 40 Mikoshi from all Shrine around Samukawa Shrine, will join this festival every years.