By Agence France-Presse
An official at the Seoul Metropolitan Police Agency's white collar crime unit said officers were investigating whether the company covered up vehicle defects and had confiscated documents and other materials.
He declined to give further details but Yonhap news agency said a team of 30 investigators were involved. There was no immediate comment from BMW Korea.
"We will conduct a thorough investigation to reveal the truth," Yonhap quoted a police official as saying.
The move came after reports more than 40 BMW vehicles have burst into flames so far this year, with some parking lots refusing to accept the cars because of fears they could catch fire.
South Korea this month temporarily banned from the streets BMW cars that had not yet passed safety checks and dozens of BMW owners filed complaints seeking a criminal investigation into the firm, its local unit and their nine top officials.
BMW Korea last month started recalling 106,000 vehicles with an exhaust gas recirculation module, which it says caused the recent fires. The recall applies to 42 models, all with diesel engines.
The company is facing a series of legal actions over the issue in the country, and has said the problem was "not Korea specific".
In South Korea, six out of 10 imported cars are from Germany, with BMW selling nearly 39,000 in the first six months of this year, according to the Korea Automobile Importers and Distributors Association.