Thongchai Jaidee (Thai ธงชัย ใจดี, born 8 November 1969) is a Thai professional golfer who plays on the Asian Tour and the European Tour. He holds the record for most career victories and most career earnings on the Asian Tour.
Thongchai did not play golf until he was sixteen, and he later went into the Royal Thai Army. He didn't turn professional until he was around thirty years old, but he soon achieved success on the Asian Tour, topping the tour's order of merit in 2001 and 2004. He first played in a major championship in the 2001 U.S. Open and finished tied 74th. In February 2004 he became the first Thai to win a tournament on the European Tour by winning the Carlsberg Malaysian Open, an event which it co-sanctioned with the Asian Tour. In 2005 he successfully defended his title. In 2006 he received a special invitation to play in the Masters Tournament. He was the second Thai to play in the Masters after Sukree Onsham, who did so in 1970 and 1971, and by doing so, he became the first Thai to play in all four major championships.
After his victory in the Volvo Masters of Asia in 2006 he reached 75 in the Official World Golf Rankings. His best year-end ranking on the European Order of Merit has been 19th in 2009. He topped the Asian Tour order of merit for a third time in 2009.