You will need Thailand visa if you want to enter this country. For a purpose of relaxing and sight-seeing, you just need a tourist visa that allow you to stay in Thailand for a period of 15 or 30 days.
A tourist is stamped on your passport upon arrival at the airport in Thailand, or it can be obtained in your home country through the Thai embassy or consular office that is located there. The tourist visa can also be extended if necessary. There are certain countries who made agreements with the government of Thailand so their citizens can benefit from the visa exemption when entering Thailand as tourists.
Period of stay
If you arrive in Thailand through an international airport, you will be stamped 1 month to 3 month permission of stay depending whether your country made a bilateral agreement on visa exemption with Thailand. If you want to stay longer than such period, you may apply for extension of stay at offices of the Immigration Bureau in Bangkok, located at Government Center B, Chaengwattana Soi 7, Laksi, Bangkok 10210, Tel 0-2141-9889 or at an Immigration office located in the provinces. Below is the summary of countries entitled for visa exemption and visa on arrival to Thailand: