Kōzō-ji, Buddhist temple in Kisarazu, Japan.

Kōzō-ji is a Buddhist temple in Kisarazu, Chiba Prefecture, holding the 30th position in the Bandō Sanjūsankasho pilgrimage circuit, a series of 33 temples dedicated to Kannon. The temple houses a statue of Shō Kannon, a specific manifestation of this revered deity.

Legend attributes the temple's founding to the brief reign of Emperor Yōmei (585–587), when the monk Tokugi enshrined a small Kannon image later placed inside one carved by Gyōki. Fujiwara no Kamatari, whose mother received a vision here, rebuilt it as a shichidō garan with a three-story pagoda. The Kannon-dō was probably rebuilt in 1526.

Kōzō-ji is the 30th stop on the Bandō Sanjūsankasho, a 33-temple Kannon pilgrimage across eastern Japan, and its amulets are valued throughout the country. Its honzon is a 3.6-metre Shō Kannon carved from a single camphor tree, once a hidden hibutsu image and now shown to visitors. Observances include Setsubun on 2 February, the Kannon Festival on 18 August and the New Year bell ringing 108 times.

Kōzō-ji stands in the Yana neighbourhood of Kisarazu, about an hour by bus from Kisarazu Station on the JR East Uchibō and Kururi lines. The temple observes Setsubun on 2 February, the equinox Higan services in March and September, the Kannon Festival on 18 August, a Segakie memorial on 24 August, and Joya no Kane, 108 bell rings, in December.

The honzon is a 3.6-metre Shō Kannon carved from a single camphor tree; it was formerly a hibutsu hidden image and is now shown to the public. Amulets issued here are valued throughout Japan. In the grounds stands a stone said to be where Fujiwara no Kamatari rested in July 650.