According to historical materials, Hyakusai-ji Temple first appears in the 11th century, 1089, therefore, it is unknown how much the legend of Prince Shotoku founding the temple reflects the historical facts, however, by seeing its jigo (literally, "temple name") - Hyakusai-ji Temple, this temple was most likely to be built as a Uji-dera Temple (temple built for praying clan's glory) for a clan formed by immigrants to ancient Japan.
百済寺の史料上の初見は11世紀の寛治3年（1089年）であり、聖徳太子創建との伝承がどこまで史実を反映したものかは不明であるが、百済寺という寺号から見て、この寺は渡来系氏族の氏寺として開創された可能性が高い。