A method of manufacturing a semiconductor device includes forming a plurality of fins by forming a plurality of first device isolating trenches repeated at a first pitch in a substrate, forming a plurality of fin-type active areas protruding from a top surface of a first device isolating layer by forming the first device isolating layer in the plurality of first device isolating trenches, forming a plurality of second device isolating trenches at a pitch different from the first pitch by etching a portion of the substrate and the first device isolating layer, and forming a second device isolating layer in the plurality of second device isolating trenches, so as to form a plurality of fin-type active area groups separated from each other with the second device isolating layer therebetween.