According to the Henley Passport Index, the Korean passport ranked number 2 on the global passport ranking (reference). Those holding a Korean passport can easily enter 192 countries with a visa-free, visa-on-arrival, e-visa, etc.
The 1st place went to Japan. The Japanese passports were more advantageous than Korean passports when entering China.
Singapore and Korea tied for 2nd place, Germany and Spain tied for 3rd place, Finland, Italy, and Luxembourg tied for 4th place, and Denmark, Netherlands, and Sweden tied for 5th place.
“The Henley Passport Index is the original, authoritative ranking of all the world’s passports according to the number of destinations their holders can access without a prior visa. The index is based on exclusive data from the International Air Transport Association (IATA). The index includes 199 different passports and 227 different travel destinations.”