Upvote:2
Malaysian citizens do not need a visa to visit Thailand. See the embassy guidelines for visa requirements.
So all you would need is a valid passport.
Upvote:4
Malaysians can enter Thailand without a visa for up to 30 days. If you plan to stay longer you need a tourist visa.
The Immigration officials may require proof of departure, for which a copy of your flight booking will suffice and they may require proof of financial support, which for a single person is 10,000 Baht or the equivalent in Ringgit (they maybe OK with a lesser amount in cash if you have a couple of credit cards from major banks).