Assuming that the name Ishibashi is derived from the name of a place, some writings including "Seishi Kakei Daijiten" (a large dictionary of Japanese surnames) state that Kazuyoshi (or Masayoshi) Ishibashi adopted his surname from a place called Ishibashi, Shimotsuke Province, but the origin of the name Ishibashi is unclear because there are many places called Ishibashi; in addition to Ishibashi in Shitara County in Mikawa Province, the Ashikaga clan's territory in the Kamakura period, or another Ishibashi in Kyoto, there are the places which were named after a stone bridge (Ishibashi literally means 'Stone Bridge') throughout Japan.
石橋の名を地名に由来するのもだとすると、『姓氏家系大辞典』等では、下野国石橋が和義の名字のもととなったと想定しているが、鎌倉期の足利家領三河国設楽郡内にも石橋の地名があるし、京都市中にも石橋の地名があり、全国各地に石の橋に因んで存在し、未だに由来が判然としない。