The effect of growth pressure on the impurity incorporation as well as on the crystal quality was investigated in sublimation growth of a bulk SiC single crystal. The growth pressure was varied within the range of 1-100 Torr and it was found that many voids or precipitates were generated in the grown crystals and the Aluminum (Al) impurity incorporation increased during the the Si-face growth when the growth pressure decreased. The pressure effect on the Al impurity incorporation with the change of step structure was discussed.