Mangetsu-ji, Buddhist temple near Lake Biwa in Katata, Japan.

Mangetsu-ji is a Rinzai-sect temple of the Daitoku-ji school in Honkatata, Ōtsu, with the mountain name Kaimon-san. Its main hall, the Kannondō, enshrines a Heian-period Shō Kannon statue and 33 Kannon images modeled after the Saigoku pilgrimage sites. The Ukimidō, a hall rebuilt in 1937, projects into Lake Biwa.

The temple was founded during the Heian Period and received a new structure in 1937, with additional repairs in 1982. These reconstructions shaped its current appearance.

The temple is also called Senbutsu-kaku or Sentai-butsu-dō, after the 33 Kannon statues in the Kannondō that copy the main images of the 33 stops of the Saigoku Kannon pilgrimage. The temple is stop 7 on the Ōmi 33 Kannon route and stop 17 on the Biwako 108 sacred sites circuit.

The temple is reachable by train to JR Katata Station, followed by a bus to Katatademachi. From there it is a short walk to the entrance.

The temple's Kannondō enshrines 33 Kannon statues modelled on the principal images of each of the 33 stops on the Saigoku Kannon pilgrimage. The hall itself, rebuilt in 1766, is a Registered Tangible Cultural Property, as are the Kyakuden (1754), Sanmon (1812) and the tea house Gyokōtei.