Headline consumer prices, which had fallen 15 months in a row, rose slightly in April on an annual basis thanks to higher prices of food, vegetables and tobacco.
The index, published by the Commerce Ministry on Monday, nudged up 0.07% in April from a year earlier. A Reuters poll forecast a 0.1% fall.
The core inflation rate, which strips out raw food and energy prices, increased 0.78% in April from a year earlier, roughly in line with the 0.71% seen in the poll.
Inflation has also been curbed by state controls and subsidies plus weak consumption amid high household debt. The Bank of Thailand has left its policy interest rate unchanged at 1.50% since April 2015.
A top central bank official told Reuters last week there was no need for a rate cut now as the economy should grow 3.1% as forecast. The BoT next reviews monetary policy on May 11.
Most analysts expect no change but some forecast a cut.