Ishiyama-dera (石山寺), formally Ishiko-san Ishiyama-dera (石光山 石山寺), is a Shingon-shu Tōji-ha Buddhist temple in Ōtsu, Shiga Prefecture. It is best known as the 13th stop on the Saigoku Kannon Pilgrimage and for its hidden honzon, a hibutsu image of Nyōirin Kannon. The temple is traditionally linked to the Nara period and has long been an important Kannon worship site. Its history reflects later rebuilding and patronage, including medieval and early modern developments that shaped the present complex. Visitors encounter a temple compound with the main worship spaces centered on Kannon devotion, along with historic architecture and temple precincts. Ishiyama-dera remains significant as both a pilgrimage site and a place of worship in Shingon Buddhism.