An object of this invention is to provide a semiconductor device in which TFTs with high mobility are arranged in both of display and peripheral circuit areas. A semiconductor device fabricating method according to the present invention includes the steps of: irradiating an amorphous silicon layer (34) with energy, thereby obtaining a microcrystalline silicon layer; and forming a doped semiconductor layer (35) on the amorphous silicon layer (34). In the step of irradiating, the amorphous silicon layer (34) is irradiated with energy that has a first quantity, thereby forming a first microcrystalline silicon layer (34A) including a channel layer for a first TFT (30A), and is also irradiated with energy that has a second quantity, which is larger than the first quantity, thereby forming a second microcrystalline silicon layer (34B) including a channel layer for a second TFT (30B).