Saitō Yoshitatsu (斎藤 義龍, July 8, 1527-June 23, 1561) was a daimyo of the Sengoku period. He is from the second generation of the Saitō clan lords.
Yoshiatsu was born in Mino province in 1527. He is the second son of Saitō Dōsan. It is possible that Yoshitatsu is actually the son of Toki Yorinari, the former master of Mino. Whether this is true or not, it helped to bring former Toki clan obligates into the service of the Saitō clan.
Yoshitatsu rebelled against his father in an attempt to take control. After decisively defeating him at the Battle of Nagara-gawa in 1556, Yoshitatsu eliminates all opposition within the clan and declares himself second leader of the Saitō.
Yoshitatsu's victory over his father encouraged many warlords, such as Oda Nobunaga for example, to fight him after his forts were deliberately destroyed and passage into Mino restricted. Yoshitatsu died of illness in 15612. The young Saitō Tatsuoki succeeded him as the third clan leader.