[6][7][8] Thammarak was born in Roi Et Province on 22 July 1938.

He is married to Wanida Isarangkun na Ayuthaya.

He is the Chief of Staff of the Deputy Chief of Staff and Special Expert of Royal Thai Armed Forces Headquarters.

[9][10] In addition, he was also Chairman of the Organization for the Transport of Goods and Parcel (ETO).

Thammarak was Deputy Prime Minister And the Minister of Defense in the government of Thaksin Shinawatra later, in 2007, political rights were disqualified for 5 years due to being the executive committee of the Thai Rak Thai Party which was dissolved in the 2006 political party dissolution case but Thammarak was sentenced to 3 years and 4 months imprisonment for not guilty on 30 May 2012 for being an official user of the organization or government agencies abusing or abusing their duties in order to cause damage to any person or performing or refraining from performing the duties dishonestly.