- June 28, 1031) was a Japanese samurai lord and gōzoku in the Heian period.
He served as Governor of Shimōsa and Vice-Governor of Kazusa Provinces, and managed the Ise Grand Shrine in fact if not in name.
The Imperial Court sought to stop him, and nominated Minamoto no Yorinobu, Governor of Ise Province, to lead the attack; he refused.
The Court then appointed Taira no Naokata and Nakahara Narimichi, who were recalled soon afterwards, after making no progress.
Knowing he could not defeat Yorinobu, Tadatsune surrendered without a fight, and was taken prisoner, perishing on the way to the capital.