According to temple legend, Hoshaku-ji Temple was founded by Gyoki on the order of Emperor Shomu in the year 724 on the southern face of Mt. Tenno (270 m), which is located on the boarder between what was once Yamashiro Province (Kyoto Prefecture) and Settsu Province (Osaka Prefecture), and has been a key transportation and military location since ancient times.
宝積寺は、山城国（京都府）と摂津国（大阪府）の境に位置し、古くから交通・軍事上の要地であった天王山（270m）の南側山腹にあり、寺伝では神亀元年（724年）、聖武天皇の勅願により行基が建立したと伝える。