Thailand's manufacturing production index (THMPI=ECI) dropped 0.8% in May from a year earlier, the industry ministry said on Tuesday, weaker than analyst forecasts.
The May reading compared with a year-on-year decrease of 0.34% forecast in a Reuters poll, and followed a revised fall of 0.94% in the previous month.
Factory output was weighed down by declining automotive production and elevated inflation, the ministry said in a statement.
Car production dropped 17.94% in May from a year earlier, according to the Federation of Thai Industries.
Continuing geopolitical conflict affected energy costs, transport, and the procurement of some imported raw materials, pushing up manufacturing and logistics costs, the ministry said.
Output was supported by government stimulus measures and stronger exports, it said.
The ministry has forecast that factory output will rise 1.0% to 2.0% this year.
Last week, the central bank left its key interest rate unchanged and raised its 2026 economic growth outlook to 2.3%, with exports seen up 14%.