The phase components, microstructure, and compressive properties of a novel Co21Cu16Fe21Ti21V21 high entropy alloy in as-cast and annealed conditions were investigated. The phase composition in both states was composed of FCC+BCC. The BCC phase was the primary phase, and the FCC phase corresponded to Cu-rich regions. Through an annealing treatment, the yield strength, σ0.2, decreased from 1950 ± 15 MPa to 1600 ±15 MPa, but the elongation of around 13% changed slightly. In this work, the solid solution strengthening in the Cu-rich regions was deteriorated due to the ejection of the rest of principal elements via annealing, while the number of microvoids seemed to be decreased against those in the as-cast alloy. The combination of both factors simultaneously takes responsibility for the decreased strength and the enhanced elongation.