Consumer confidence fell for a third straight month in March, hitting a nine-month low.
Thai consumers said the country's economy had not recovered much and the cost of living was still rising despite stabler politics.
The University of the Thai Chamber of Commerce (UTCC) said Thursday the consumer confidence index fell to 77.7 points last month from 79.1 in February, 80.4 in January and 81.1 in December, which was the highest since June 2013, when the index reached 81.6.
"People are feeling dejected, as farm prices have yet to show signs of recovery and negative information is continuously reported, be it the bearish outlook for exports, government attempts to raise the land and property tax, value-added tax and inheritance tax or the higher cost of living and falling farm prices," said Thanavath Phonvichai, vice-president for research.
"Moreover, several agencies have painted negative prospects for the Thai economy, thus weakening Thai consumer confidence."
The central bank recently slashed its economic growth forecast for the year to 3.8% from 4%, while Kasikorn Research Center trimmed its growth prediction to 2.8% from 4% based on an assumption of flat export growth.
Mr Thanavath said the economy might grow by 3% to 3.5% this year, down from an earlier projection of 3.5% to 4%, with exports to see flat or 1% growth instead of the 1% to 2% previously forecast.
The UTCC is due to unveil its latest economic forecast on April 16.
Mr Thanavath said consumption would remain weak through the second quarter.
How fast consumption and confidence will recover will depend largely on state budget disbursement and a recovery in exports.
The central bank may cut its benchmark rate again if the economy shows no signs of recovery in the second quarter.
"The second quarter is the key turning point for the country's economic system," Mr Thanavath said.
"The government has to produce concrete action to stimulate economic growth, work out measures to curb the baht's strength to boost exports and restore consumer confidence."
He said the recent revocation of martial law would be positive for the economy, notably tourism, as foreign tourists would feel more at ease about travel to Thailand.