Ishida Masatsugu (石田 正継, ? - October 23, 1600) was a Japanese samurai of the late Sengoku period who served the Azai clan and held Ishida castle in Omi province.[1] He was the son of Ishida Seishin. He was the father of Ishida Mitsunari.[2][unreliable source?][3] After the Battle of Sekigahara in 1600, he and his other son, Masazumi, committed suicide at Mitsunari's Sawayama Castle in Omi province.