An excessive metallic film on a device isolation region is prevented from contributing to silicidation in an end of a source-drain diffusion layer region to thereby form a silicide film with uniform film thickness. There are sequentially conducted a step of forming a device isolation region 3 in a substrate 1 including a silicon layer at least in a surface thereof and filling a first insulator in the device isolation region 3, a step of making height of an upper surface of the first insulator less than height of an upper surface of the substrate 1 and forming a sidewall film 10 on a sidewall of the device isolation region 3, and a step of depositing a metallic film 11 on the substrate 1 and then conducting silicidation through a thermal process.