Provided is a high voltage transistor in a flash memory device comprising: a source/drain junction of a DDD structure consisting of a high-concentration impurity region and a low-concentration impurity region surrounding the high-concentration impurity region, the high-concentration impurity region being formed in parallel with a gate electrode at a distance spaced by a location in which a contact hole is formed, and having a rectangular shape whose width is the same as or wider than that of the contact hole and whose length is the same as or narrower than that of an active region through which the gate electrode passes. Accordingly, a current density to pass the gate electrode neighboring the contact hole portion and a current density to pass the gate electrode at a portion where the contact hole cannot be formed become uniform. A uniform and constant saturation current can be obtained regardless of the number of the contact hole.