普門院, Buddhist temple in Asakura, Japan

Fumon-in is a Shingon Buddhist temple of the Koyasan branch in the Haki area of Asakura, Fukuoka Prefecture. Its main hall, built between 1275 and 1332, has a three-bay square plan, a pyramidal hip roof covered in tiles, and a three-bay worship porch. The temple's principal image is an eleven-faced Kannon.

Tradition holds that the monk Gyōki founded Fumon-in in 747 as the betsu-ji of Matarafu Shrine; the temple later moved from near the Chikugo River to its present site. Kūkai is also said to have stayed here. In the Ōnin years (1467–1469) fire destroyed the temple and its old records.

Fumon-in was the betto-ji, the temple administering the nearby Madarafu Shrine, a role recorded in its history. The temple belongs to the Koyasan Shingon school and honours an eleven-faced Kannon statue from the Heian period, designated an Important Cultural Property in 1912.

The temple is accessible by public transportation and has designated areas for prayer and meditation activities. Visitors can explore the grounds at their own pace and should respect the spaces set aside for religious practice.

The temple's bronze bell, cast in 1736, bears an inscription naming the local patrons who funded it. It hangs in a small bell tower beside the main hall and is still rung on New Year's Eve.