Automotive output in May dropped by 6.11% year-on-year to 181,338 units on an export slowdown, the Federation of Thai Industries (FTI) said on Thursday.
The output represented a 20.7% increase from April.
Surapong Paisitpatanapong, spokesman of the FTI's automotive industry club, said the production of passenger cars and pickup trucks for exports fell last month.
Auto exports in May fell 3.6% to 95,331 units on a slowdown in markets such as Oceania, Central and South America and Africa. In baht terms, they dropped by 6.2% to 48.65 billion baht.
Domestic car sales totalled 88,097 units last month, up by 3.7%, on improved local sentiment.
"The auto market was driven by the government's supportive measures in the past for farmers and low-income earners. They helped increase spending and circulation in the country.
"New investment plans from both public and private sectors and the growing number of visitors to Thailand remain healthy to support overall gross domestic product and the auto market," Mr Surapong said.