The inventive concept provides an optical proximity correction (OPC) method using a multi-OPC model that can reduce a runtime of an entire OPC method by reducing an iteration number of simulations using a complex OPC model, and a method of manufacturing a mask by using the OPC method. The OPC method using the multi-OPC model can generate a re-target pattern to be applied to a simple OPC model, and can perform a simulation by using a complex OPC model on a target pattern after performing a simulation using the simple OPC model on the re-target pattern. Therefore, an iteration number of simulations using the complex OPC model can be reduced and, accordingly, an entire execution time of the OPC method can be reduced.