Grain refinement is an effective way to increase both of strength and toughness of structural materials. Carbon inoculation is the most effective technology among the various grain refinement methods for Mg alloys containing Al. A typical method of carbon inoculation is to add a carbon containing agents such as carbonate, carbon gaseous materials, carbide, etc. SiC is well-known as an effective carbon containing agent for grain refinement. However, conventional SiC inoculation methods such as using SiC powder itself, using a master alloy made through powder metallurgy, etc., have shown unstable refining ability, low efficiency, and non-economical processes in terms of application in industry fields. This study investigates the inoculation method how to use of SiC effectively, economically for grain refinement of Mg alloys containing Al. And mechanical properties related to changes in microstructure features were also investigated.