Wide band gap semiconductors doped by transition metals are attracting much attention in part because of possible 'spintronics' applications. Using pseudo-potential plane-wave calculations and density functional theory (DFT), we studied effects of doping Mn of various concentrations on the cubic silicon carbide structure (-SiC). Band structures and density of states (DOSs) were calculated for -SiC and Si 1-x Mn x C (with x= 0.0313, 0.0625, and 0.25). Analyses of the DOSs revealed that the diluted ferromagnetic semiconductor Si 1-x Mn x C, i.e. SiC with Mn substituted for Si, should be a half-metal. Our results show spin polarization at Fermi energy (E f ), and a stable ferromagnetic state for x= 0.0625.