To improve the characteristic of a MOS transistor in a peripheral circuit area, by forming the first source/drain areas of a memory circuit area with a single area, and providing a first metallic silicide layer on the surface of the second source/drain areas of the peripheral circuit area.

First source/drain areas 6 and 7 of a first MOS transistor in the memory circuit area are formed by the single impurity area. First metallic silicide layers 21a and 21b are provided for second source/drain areas 22a and 22b of the second MOS transistor in the peripheral circuit area. Since the metallic silicide layer is not formed in the first/drain areas 6 and 7, the deterioration of the characteristic of the memory circuit owing to the occurrence of a crystal defect and the occurrence of junction leak can be avoided. The wiring resistance of the second source/drain areas 22a and 22b can be reduced and junction capacity can be reduced.