Phetracha was born in 1632 at Baan Plu Luang, Suphanburi. De la Loubère has recorded that he was a cousin of King Narai, and that his mother was also King Narai's milkmaid. It was also recorded that his sister was one of King Narai's queens.
He started his civil service career as master of the royal elephants, which was a high military position. Hence, he was sometime referred to as "the Elephant Prince".