In this study, a non-equiatomic high entropy alloy was fabricated using the spark plasma sintering method, and its microstructural features and mechanical properties were investigated. The chemical composition of FeMnCoCr was determined by using the entropy calculation related to the design of high entropy alloys. A bulk sample with the same composition was also prepared using the conventional metallurgical processes of casting and hot rolling. The microstructures of the samples fabricated by these different processes were compared by microscope observation, and a quantitative phase analysis was carried out using FE-SEM. Hardness measurement was used to evaluate mechanical properties. Particular attention was paid to microstructural changes due to heat treatment, which was analyzed by considering how austenite stability is affected by grain refinement.