Police arrested Jirachai Lertbamroon, 32, on Tuesday at a monastery in Singburi province where he was the acting abbot, said police Col. Jirasak Suriyawong. Jirachai was taken to Bangkok, where he allegedly committed the crime, to face charges, Jirasak said.
The suspect, also known by the monk's name of Phra Uthano, told police that he stole two pistols from the home of retired police Gen. Thassana Klongpayaban in Bangkok and sold them for 30,000 baht (US$750).
"The suspect claimed he needed money to buy materials for the construction of a temple pavilion, but investigators believe he needed the money to pay personal debts," Jirasak said.
Police said he was charged with stealing and faces a maximum penalty of three years' imprisonment if found guilty.
More than 90 percent of Thailand's 62 million people are Buddhist. Building pagodas, chapels and pavilions are seen as an ideal way for Buddhist followers to make merit.
Thailand's 500,000 monks and novices are supposed to live modestly and in celibacy, but there have been several prominent cases of them committing crimes, having sex with women, abusing drugs and even murdering.
Singburi province is 120 kilometers north of Bangkok.