Abstract: A high-voltage semiconductor device and a method of manufacturing the high-voltage semiconductor device are provided. For example, with the above device and method drift regions having first depths are formed in a semiconductor substrate by doping first impurities. The drift regions are spaced apart from each other to define a channel region between the drift regions. Source/drain regions having second depths are formed at first portions of the drift regions by doping second impurities. Impurity accumulation regions having third depths are formed at second portions of the drift region adjacent to the source/drain regions by doping third impurities. A gate insulation layer pattern is formed on the semiconductor substrate to partially expose the source/drain regions. A gate conductive layer pattern is formed on a portion of the gate insulation layer pattern where the channel region is positioned.