High-quality ZnSe single crystals are grown by the sublimation method in which the seed crystal is used and Ar gas is enclosed for the control of growth rate. Also, vapor pressure control is performed by adding Zn or Se element into the growth chamber. X-ray rocking curves, etch pit densities and photoluminescence spectra are measured and it is found that the crystal properties systematically change with deviation from stoichiometry by the vapor pressure control. The minimum dislocation density is 3.1 x 10(3) cm(-2). Also, it is found that the growth rate depends on the Se, or Zn partial pressure and not only on the total pressure.