A total of 465 logs were found in the room, said Mekhong Riverine Unit chief Arak Kaewiam. A white pickup truck was also taken in as evidence.
No suspect was found at the location, he said.
Rear Adm Arak said a navy commander was tipped off on Sunday that an unknown group has been stashing illegally harvested logs, which would be smuggled out.
He believes the logs would be sold to clients in neighbouring countries.
The logs are being kept at the Nikhom Kham Soi police station. The police will conduct further investigation to track down the group behind the operation.