本行寺, Buddhist temple in Sumida-ku, Japan.

Hongyō-ji is a Nichiren Shōshū temple in Sumida-ku, facing Jōsen-ji across Kōmon-dōri. Its main hall is a three-storey reinforced-concrete building, rebuilt in 1972. The temple's mountain name is Risshō-zan.

Founded in 1638 as a sub-temple of Jōsen-ji by the fifth abbot Hongyō-bō Nichiyū, it became affiliated with Taiseki-ji that same year. In 1911 it absorbed the sub-temple Honshu-in (Nichiudō). It was destroyed in the Tokyo air raid of March 10, 1945, and rebuilt with a reinforced concrete main hall in 1972.

The temple belongs to the Nichiren Shoshu school, and its mountain name is Rissho-zan. It was founded in 1638 as a sub-temple of Josen-ji by Hon'gyo-bo Nichiyu, the fifth abbot of Josen-ji, who converted in the same year. Josen-ji, also Nichiren Shoshu, stands across Kototoi-dori from it.

Hongyouji stands on the north side of Kototoi-dori, directly across the road from Jousenji, another Nichiren Shoushuu temple. It is a 4-minute walk from Tokyo Skytree Station on the Tobu Isesaki Line, 8 minutes from Honjo-Azumabashi on the Toei Asakusa Line, and 11 minutes from Oshiage Station. Sumida Park and Kototoi Bridge are also about 4 minutes on foot.

The temple absorbed the neighbouring sub-temple Honshu-in (Nichiudo) in 1911, and in 1938 hosted the completion ceremony for the 134-volume Fuji Shugaku Zenshu, compiled under the 59th abbot of Taisekiji, Nichiko. The current main hall, rebuilt in reinforced concrete over three floors in 1972, stands across Kototoi-dori from the related temple Josen-ji.