District courts have ruled that providing lodgings through accommodation sharing service provider Airbnb is illegal if the owners do not report operating the service to the relevant authorities.
The rulings are expected to affect many such people who do not make the reports.
The Seoul Central District Court fined a woman, surnamed Han, 700,000 won for running illegal accommodation business using Airbnb from April to May this year.
Han offered her officetel room in central Seoul to foreign tourists at a cost of 100,000 won per night.
Under the law governing public health and safety, those who run accommodation businesses must obtain permits from the relevant district office, which she failed to do.
Similarly, Busan District Court last month fined a woman, surnamed Chung, the same amount for charging travelers 200,000 won per night at her residence in Haeundae since July last year until February this year.
The rulings have come amid growing complaints from hotel operators who claim many Airbnb hosts offer the service illegally, in order to be exempt from tax and related regulations.
Established in 2008 in San Francisco, its service is available in 34,000 cities in more than 190 countries with 1.5 million hosts.
Since the service launch here in January 2013, the service has gained huge popularity with more than 180,000 users, and around 11,000 hosts.
Many hotel operators have filed complaints with the police demanding a crackdown on such operations that hurt their business.
But an official from Airbnb said that the agency already gives hosts instructions to check the related regulations in their respective countries to avoid punishment.
About government permission or other rules, he said it was difficult to provide identical advices to different countries.
"We take care of our hosts by providing the most needed information on the website," the official said.
Airbnb is like Uber, a ride-sharing service. Although both are gaining international recognition as successful business model, they have drawn heavy criticism from the existing business for not being subject to the same government regulations and taxes.
The Korean unit of Uber and its head Travis Cordell Kalanick are currently on trial on charges of operating illegal transport services.