An object of the present invention to provide a semiconductor device having a highly functional memory element with improved reliability, and to provide a technique for manufacturing such a highly reliable semiconductor device with a high yield at low cost without complicating an apparatus or a process. As a top view shape of a memory element, a rectangular shape having a projection and a depression on the periphery, a zigzagged shape having one or plural bends, a comb shape, a ring shape having an opening (space) inside, or the like is used. Alternatively, a rectangle with a ratio of a long side to a short side being high, an ellipse with a ratio of a long axis to a short axis being high, or the like can also be used.