This study was conducted to develop HTHP ginseng (high temperature and high pressure ginseng) with improved antioxidative activity and phenolic acid composition by high temperature and high pressure process. The HTHP ginseng extract was analyzed for the total phenol content, DPPH radical scavenging activity and phenolic acid composition. The total phenol content was increased in HTHP ginseng (14.76 ㎎/g) compared to raw ginseng (3.59 ㎎/g) and red ginseng (3.93 ㎎/g). DPPH radical scavenging activities of HTHP ginseng, raw ginseng and red ginseng extracts were 4.8～78.4%, 1～47.4% and 1.8～56.5% at 1～100 ㎎/㎖ concentration. Also ABTS radical scavenging activities of HTHP ginseng, raw ginseng and red ginseng extracts were 8.9～99.8%, 3.4～96% and 1.2～96.5% at 1～100 ㎎/㎖ concentration. In HPLC analysis, amounts of measured phenolic acid of HTHP ginseng greatly increased than raw ginseng and red ginseng, but salicylic acid was not detected in HTHP ginseng. In addition, DPPH radical scavenging activity of phenolic acid from HTHP ginseng was increased. Consequently, we believe high temperature and high pressure process is better method than existing method to increase the bioactivity of ginseng.