To provide a method of efficiently configuring a circuit requiring high inter-device consistency by using thin-film transistors. A semiconductor layer is formed on a substrate and is patterned into desired shapes to form first semiconductor islands. The first semiconductor islands are uniformly crystallized by laser irradiation within the surface areas thereof. Thereafter, the semiconductor layers are patterned into desired shapes to become active layers of the thin-film transistors layer. Active layers of all of thin-film transistors constituting one unitary circuit are formed of one of the first semiconductor islands in this case. Thus, the TFTs mutually realize high consistency.