Charging services for electric vehicles (EVs) in commercial facilities have become common in recent years. The design of a charging service provided to EVs is an important factor affecting the number of visitors and the rate of revisit for commercial facilities. A major requirement for EV charging services is maintaining fairness for service recipients while supplying chargeable electric power to multiple EVs, even in peak demand situations, to avoid affecting contracted power, which is a dominant factor in utility rates. In this study, the authors propose a charging prioritization scheme that monitors the state of charge (SOC) of multiple EVs. The proposed method explicitly introduces the priority weight as a function of individual SOCs to control the required charge amount per parking time for EVs with relatively high urgency. The relationship between the parameter in the weighting function for prioritization and the charging achievement rate is analyzed by conducting simulation experiments based on a dataset collected at a real-world commercial facility. The results show that the appropriate assignment of the proposed prioritization function allows control of the charging achievement rate of each EV without violating the contracted power of the facility.