Songtham (Thai: ทรงธรรม) was the King of Ayutthaya from 1620 to 1628 of the House of Sukhōday. His reign was marked as prosperity of Ayutthaya kingdom after regains independence from Toungoo Dynasty and saw the commencement of trade with foreign nations especially the Dutch and the Japanese. Songtham filled his guards with foreign mercenaries most notably the Japanese – Yamada Nagamasa.
Songtham wanted his son, Chettha, to succeed him, though he was young. He therefore asked Phraya Siworawong or Prasat Thong, to protect him from danger. After Songtham's death, Siworawong arrested and executed all those who had been opposed to Songtham's wishes.