Are there restricted dog breeds in Korea?

Yes, Korea legally designates certain breeds as dangerous dogs (맹견), with specific rules. The designated breeds are the Tosa, American Pit Bull Terrier, American Staffordshire Terrier, Staffordshire Bull Terrier, Dogo Argentino, and mixes of these. If you own one, the law requires a muzzle in public for dogs over three months old, a leash at all times, and mandatory liability insurance for the dog, and these dogs are barred from places like daycare centers, kindergartens, elementary schools, and some welfare facilities; a handling permit requirement for designated breeds is also being phased in.

For dogs generally, not just the designated ones, Korea has a nationwide leash rule in public, dog registration (동물등록) is mandatory for dogs over two months, and you must carry waste bags and keep the dog controlled in elevators and shared apartment spaces (many complexes ask you to hold or muzzle any dog in the elevator). Fines apply for an unleashed dog or a missing muzzle where required. So if your large or powerful dog is not on the designated list, the main things are the leash rule, registration, and insurance being a very good idea; if it is on the list, the muzzle, leash, and liability insurance are legal requirements. Rules have been tightening, so check the current Animal Protection Act, and your vet or the district office can confirm what applies to your specific dog.