Most foreign nationals visiting Korea are required to have a visa issued by the Korean embassy or consular offices in their country. An online visa application is available at the Korea Visa Portal (link opens on Chrome and Internet Explorer).
Citizens from a few dozen countries and territories do not need visas for visits of 30 to 90 days, including Japan, Hong Kong, Macao, Taiwan, Australia, Canada and the United States.
Don’t wait to apply for a visa, as wait times can be several weeks. Make sure your passport is valid for at least six months and that you don’t need a transit visa to change planes in some countries.