The trade-off between breakdown voltage, V-br and a specific on-state resistance, R-ons of SiC devices is several hundred times better than the equivalent Si devices, due to SiC having a higher critical electric field, E-c. However, this evaluation method is only valid for the static on-state loss characteristics of devices. It is important to determine the advantage of SiC devices considering the total power dissipation in the device including switching loss for the practical use of the devices. The product of R-ons and a stored charge Q(o) in a drift region, R(on)Q(o) corresponding to switching loss has been recognized as a general figure of merit for power device evaluations [1-3]. In this paper a total power dissipation, P-t, defined as a summation of a on-state loss, P-on, a gate driving loss, P-i and a switching loss, P-o, is theoretically studied, considering the figure of merit. The purpose of this paper is to reinforce the advantages of 4H-SiC uni-polar devices in comparison with equivalent Si devices and outline the technical issues to be solved for these advantages to be realized.