A shielding layer 23 is selectively formed on a single crystal silicon layer, an active area 25 is formed in the single crystal silicon layer by using the shielding layer 23 as a mask and an impurity layer 26 is formed at the edges at the sides of the active area 25 by using the shielding layer 23 as a mask and implanting an impurity diagonally from above. As a result, since an impurity layer can be formed by implanting ions of the impurity at the edges at the sides of the active area even when the size of the active area is reduced to the absolute limit, the occurrence of the parasitic transistor phenomenon or the edge transistor phenomenon along the edges at the sides of the active area can be prevented.