Phrabat Somdet Phra Ratsadathirat () (1529 - 1534) was the king of Ayutthaya from 1533 to 1534 - only for 5 months. Prince Ratsadathirat was the son of Borommaracha IV who died suddenly in 1533 from an epidemic. Prince Ratsadathirat, aged 5, succeeded his father as the king of Ayutthaya. Due to his minority, his government was dominated by a number of regents including the Samuha Nayok and the Samuha Kalahom.

In 1534, his uncle Prince Chairacha who was the Uparaj at Pitsanulok staged a coup and executed Ratsdadathirat and then assumed the throne of Ayutthaya.
Category:1529 birthsCategory:1534 deathsCategory:Thai monarchsCategory:Rulers of Ayutthayade:Ratsadaja:ラッサダーティラートクマーンth:สมเด็จพระรัฏฐาธิราชกุมาร