In a p-type MOS transistor, a gate electrode is partially removed by a predetermined wet etching, so that an upper portion of the gate electrode is formed to be lower than an upper portion of a sidewall insulation film. As a result of such a constitution, in spite of formation of a tensile stress (TSEL) film leading to deterioration of characteristics of a p-type MOS transistor by nature, stresses applied from the TESL film to the gate electrode and the sidewall insulation film are dispersed as indicated by broken arrows in the drawing, and consequently, a compressive stress is applied to a channel region, so that a compressive strain is introduced. As stated above, in the p-type MOS transistor, in spite of formation of the TESL film, in reality, a strain to improve characteristics of the p-type MOS transistor is given to the channel region.