Thailand's manufacturing production index in December fell 6.27% from a year earlier as car production output declined, the Industry Ministry said on Wednesday.
The figure compared with a forecast for a 3.2% year-on-year fall for December in a Reuters poll, and followed November's 4.71% decrease.
Output contracted 5.11% in the whole of 2023.
December's output decline was also due to high household debt and borrowing costs as well as economic growth downgrades, the ministry said in a statement.
Thailand's household debt was at 90% of gross domestic product (GDP) as of the third quarter of last year.
"There are more cautious signs in January, mostly economic concerns, Warawan Chitaroon, head of the Office of Industrial Economics (OIE), told a briefing.
Last week, the Finance Ministry slashed its 2023 economic growth forecast to 1.8% from 2.7% seen earlier. It also expected growth in 2024 to slow sharply to 2.8% from a previous forecast of 3.2%.
The government has repeatedly said the economy is in crisis and needs a big boost from its $14 billion digital handout scheme.