Police estimate the drugs had a street value of about B100,000.
Capt Suchart Luecha of the Thalang Police led the raid, carried out at 6:40pm, after a tip off from undercover officers.
“Before the raid, we learned that the house belonged to Sanong Ngankhang 46,” Capt Suchart said.
“Mr Sanong was arrested on drug charges and released from prison three years ago,” he added.
When police raided the site, they found Sanong along with Somchai Chuanchit, 51, Wisarut Dujpajack, 28, and Jaturong Naksarn, 25, on the premises.
“We searched them and the area around the shack and found in total 40.2 grams of heroin in small containers as well as drug-taking paraphernalia,” Capt Suchart said.
Police also seized other items such as bamboo bongs, straws and plastic bags.
“At first all of them admitted to taking the drug, but denied that the drugs found belonged to them,” Capt Suchart said.
“But later after they all tested positive for the drug, they admitted that the drugs found belonged to Sanong,” he added.
All four men were taken to Thalang Police Station, where they were charged with illegal possession of Category 1 (heroin) with intent to sell.