Microsoft will stop providing security updates and patches as well as online technical support for the 13-year-old XP operating system.
Estimates suggest that almost one in five PCs still run XP. While consumers are entitled to use it as long as they like, those who choose to do so will be more vulnerable to cyber attacks.
Most ATMs in Korea also use XP, raising concern that they could be prone to security risks.
Microsoft is advising Windows XP users to consider upgrading to Windows 7 or 8.