It has been thought that PCS(persistent-current-switch) give higher efficiency of SMES. However, the effects of PCS in SMES have not been made clear. We calculate here the efficiencies for some cases of SMESs (55MWh∼5.5GWh) with PCS for load leveling. As types of the PCS we assume normal mechanical type, cryogenic mechanical type, semiconductor type. We compare the case of converter-circulation operation with that of the PCS-circulation operation for a daily load leveling operation. As a result, the storage efficiency of PCS-circulation is proved to be several percents higher than that of converter-circulation.