Any foreign visitors wishing to enter the Republic of Korea must have a valid passport and obtain a Korean visa before coming.
However, nationals of visa waiver countries can enter Korea without a visa as long as the purpose of their visit is tourism or temporary visit.
Please refer to http://www.hikorea.go.kr/pt/InfoDetailR_en.pt for more information.
Visa application should be made at Korean embassies or consulates abroad. It is required that visa applicants submit a passport, application forms, a recent passport-style color photograph, and such other documents as determined by the status of stay.
Visa fees vary depending on nationality. Check with the nearest Consulate for further information.