A novel design concept called high entropy alloys (HEAs) has been getting attention owing to their superior properties such as high strength, high ductility, high corrosion resistance, etc. However, recently, some reports questioning the role of “high entropy” have been published, which indicate that the origin of the outstanding properties is still unclear. In this study, we focus on vacancy diffusion in equiatomic multicomponent alloys. Various kinds of FCC single phase equiatomic multicomponent alloys composed of Co, Cr, Fe, Ni, Mn (e.g., FeNi, CoFeNi, CoCrFeNi, etc.) were fabricated by using vacuum arc-melting furnace. The formation energy and migration energy of vacancies were determined using positron annihilation spectroscopy as a vacancy probe. The contribution of entropy and enthalpy to the properties of CoCrFeNiMn HEA and its subsystems will be discussed to understand the essential characteristics of equiatomic multicomponent alloys from a viewpoint of point defects.