The plasma in water is generated by applying high-frequency (HF) irradiation of 27.12 MHz or microwave (MW) radiation of 2.45 GHz from an electrode. The electrode is heated by joule heating by the HF or MW irradiation, and vapor bubbles are generated simultaneously. The plasma is then ignited inside the bubbles on the electrode. The glow discharge plasma can be maintained in spite of atmospheric pressure due to the cooling effect of the liquid itself. The electron temperature of the plasma generated by the 27.12 MHz radiation is higher than that generated by the 2.45 GHz radiation. (C) 2008 The Japan Society of Applied Physics.