Silicon, carbon, and B4C powders were used as raw materials for the fabrication of porous SiC. ${eta}$-SiC was synthesized at $1500^{circ}C$ in an Ar atmosphere from a silicon and carbon mixture. The synthesized powders were pressed into disk shapes and then heated at $2100^{circ}C$. ${eta}$-SiC particles transformed to ${alpha}$-SiC at over $1900^{circ}C$, and rapid grain growth of ${alpha}$-SiC subsequently occurred and a porous structure with elongated plate-type grains was formed. The mechanism of this rapid grain growth is thought to be an evaporation-condensation reaction. The mechanical properties of the fabricated porous SiC were investigated and discussed.