To drive or rent a car in Thailand as a tourist or visitor it is necessary to have either a Thai driving licence or a valid foreign driving licence with a photograph. The foreign licence must either be in English, or be accompanied by an official translation into English or Thai. The licence needs to have been issued by a country that has a treaty with the Thai government allowing the mutual acceptance of driving licences. Most countries, including Australia, Canada, New Zealand, the UK and the USA have this agreement with Thailand under the 1949 Geneva Convention on Road Traffic or the 1968 Vienna Convention on Road Traffic. Those in doubt should contact their embassy for advice. 06 Jul 2012 motor vehicle act; Motor Vehicle Act – B.E. 2522.
So, if you are visiting Thailand as a tourist and you want to rent a car, you just need to carry the driving licence you obtained in your home country as clearly indicated in the Motor Vehicle Act: Section 42-2.
However………………. the Thai Police in Thailand will often act completely unaware of the 1949 Geneva Convention on Road Traffic or the 1968 Vienna Convention on Road Traffic so you will often get a small fine of 400 baht for not having either a Thai Driving Licence or an International Driving Permit,
Unfortunately that is just how it is here in Thailand