In this paper, the pulsed mode operated gas discharge tube is composed with mixed gas of Hg-Ne (10 Torr), in the tube of 15.0 mm outer diameter and has variable color from red to blue with changing frequency high voltage. As increasing frequency in the gas discharge tube, the phenomena, that the electron temperature in the positive column increases and the radiation from atoms of higher upper state energy levels increases, exist The color have the locus from red (0.4972, 0.3128) to blue (0.2736, 0.2619) in CIE chromacity diagram with increasing frequency. The method of changing frequency has been shown to be suitable for the luminous color control.