The migrants were found on a rubber plantation in Takua Pa district in the southern coastal province of Phang Nga, district chief Manit Phianthong told AFP.
"We got a tip-off from an informant that a trafficking gang would be transporting Rohingya people to Malaysia," he said, adding that the migrants came from Myanmar's western Rakhine state and Bangladesh.
Thousands of Rohingya - a Muslim minority group not recognised as citizens in Myanmar - have fled deadly communal unrest in Rakhine since 2012, mostly heading for Malaysia.
"We are still looking for the real masterminds," said the official.
Twelve Rohingya migrants are thought to have escaped during the raid, he added.
Myanmar views its population of roughly 800,000 Rohingya - described by the United Nations as one of the most persecuted minorities in the world - as illegal Bangladeshi immigrants, and denies them citizenship.
They face travel restrictions, forced labour and limited access to healthcare and education.
Rights groups say the stateless migrants often fall into the hands of unscrupulous people traffickers.
They have also criticised Thailand in the past for pushing boats of Rohingya entering Thai waters back out to sea and holding migrants in overcrowded facilities.
Thailand said last year it was investigating allegations that some army officials in the kingdom were involved in the trafficking of Rohingya.
