A 60-year-old South Korean man ran a private museum stuffed with fakes, police said as they arrested him.
The man collected 530 million won ($443,000) from people who thought the objects on display were ancient treasures, AFP news agency reported.
The man, who police named only as Mr Yu, is said to have bought ceramics and other items from flea markets.
The museum was set up in August 2004 and has attracted more than 130,000 visitors, police said.
Police told AFP that 153 of the 184 artefacts on display at the museum in Gongju, about 160km (100 miles) south of the capital, Seoul, were fakes.
Mr Yu had apparently claimed his collection included artefacts of "Koryo Dynasty celadon" dating to the 10th-14th centuries.
He had pretended to be a herbal medicine doctor with a doctorate and various citations from the president and prime minister, police said.
AFP also reported that he is suspected of taking 240 million won prescribing fake cures to patients.