Kōzaki-jinja, Shinto shrine in Kozaki, Chiba Prefecture, Japan

Kōzaki-jinja is a Shinto shrine in Kozaki, Katori District, Chiba Prefecture, formerly a prefectural shrine (kensha). Its three principal deities are Ameno-torifune-no-mikoto, Ōnamuchi-no-mikoto and Sukunabikona-no-mikoto. In the grounds stands the Kozaki Giant Camphor, a national Natural Monument: a main trunk 13.1 m around at the base and 19 m tall, ringed by five suckers, popularly called the Nanjamonja tree. The shrine grove is a Chiba Prefecture Natural Monument.

According to shrine tradition, the shrine was founded in 673 (Hakuhō 2), when its deities descended from the two mounds of Ōura Pond on the Hitachi-Shimōsa border. It was called Komatsu Shrine until the Meiji period and received the junior fifth rank, lower grade, in 879 (Gangyō 3). In the Sengoku period it held 700 chō of shrine land, and in the Edo period 20 koku under the shogunate's vermilion-seal grant.

Until the Meiji period the shrine was called Komatsu Jinja; in 879 it received the junior fifth rank, lower grade. Its three deities are Ameno Torifune no Mikoto, Ōnamuchi no Mikoto and Sukunabikona no Mikoto. The grounds hold a camphor tree nicknamed Nanjamonja no Ki, a protected natural monument: five suckers ring the trunk, whose base measures 13.1 m around at a height of 19 m.

Kōzaki-jinja is about a 20-minute walk from Shimōsa-Kōzaki Station on the Narita Line. By road it stands near the south end of the Kōzaki Bridge, where National Route 356 meets the Ibaraki–Chiba prefectural road 107 (Edosaki–Kōzaki line). The shrine grounds also hold the great camphor and the shrine grove.

The shrine grounds hold the Kozaki Giant Camphor, a national Natural Monument: a main trunk 13.1 m around at the base and 19 m tall, ringed by five suckers. Locals call it the Nanjamonja tree. The shrine grove around it is a Chiba Prefecture Natural Monument, the Kozaki Forest.