A FinFET is provided. The FinFET includes a substrate. A plurality of fin structures are defined on the substrate. A gate structure crosses each fin structure. Two first recesses are disposed on two sides of the gate structure respectively, wherein each first recess further includes a plurality of second recesses disposed therein, and the position of each second recess corresponds to each fin structure. Two epitaxial layers are disposed at two sides of the gate structure respectively and in the first recesses, each epitaxial layer has a bottom surface including a second concave and convex profile, and each epitaxial layer directly contacts a bottom surface of each first recess and a bottom surface of each second recess.