Method of manufacturing a semiconductor device having fin-field effect transistor

A semiconductor device includes an element isolation region formed in a semiconductor substrate, an active region surrounded by the element isolation region, and a gate electrode formed in one direction to cross the active region. The semiconductor substrate includes two gate trenches formed in parallel to a major axis direction of the active region in the active region, and a fin-shaped part which is located between the two gate trenches. The gate electrode is buried in the two gate trenches and formed on the fin-shaped part. The fin-shaped part serves as a channel region. A fin field effect transistor in which a width of the channel region is smaller than a gate length is thereby obtained.