A drain diffusion layer 11b includes a low impurity concentration region 5a and a high impurity concentration region 5b, and the low impurity concentration region 5a is located on the channel region side. An impurity layer 7 having an opposite conductivity type to the drain diffusion layer 11b is formed in the channel region, at a position away from the low impurity concentration region 5a by a distance T. Alternatively, the low impurity concentration region 5a and the impurity layer 7 are located so as to contact each other. Still alternatively, a border impurity layer is provided between the low impurity concentration region 5a and the impurity layer 7. Thus, a semiconductor device including a high voltage transistor capable of suppressing the reduction of the electric current driving capability and performing stable driving, and a method for fabricating the same, can be provided.