An optical proximity correction (OPC) method may include providing a design layout including conductive patterns, determining line end void (LEV)-risk patterns among the conductive patterns, the LEV-risk patterns each having a risk of suffering from poor contact due to an LEV, setting markers including portions of the LEV-risk patterns and portions of the conductive patterns adjacent to the LEV-risk patterns, performing a first OPC on first patterns included in the markers and performing a second OPC on second patterns outside the markers, the second OPC being different from the first OPC, and each of the first OPC and the second OPC being performed a plurality of times, and calculating a cost function of each of the markers. The determining may include comparing risks of occurrence of poor contact in each of the conductive patterns based on a scoring function, and the scoring function may be inversely proportional to a width of each of the conductive patterns.