To provide a semiconductor device and its manufacturing method for reducing thermal damage to be received by a film formed at the lower part of a transistor during of forming the transistor.

This method for manufacturing a semiconductor device comprises a process for forming a shielding film 38 on a first insulating film 37; a process for successively forming a second insulating film 39 and an amorphous semiconductor film 40 on the shielding film 38; a process for irradiating the amorphous semiconductor film 40 with an energy beam, and for fusing at least the amorphous semiconductor film 40 at a section which becomes the channel of the thin film transistor to form a multi-crystal semiconductor film 41; a process for successively forming a gate insulating film 43a and a gate electrode 44a on the multi-crystal semiconductor film 41 on the channel; and a process for forming a source/drain area 41a on the multi-crystal semiconductor film 41 beside the gate electrode 44a, and for configuring a TFT 60 of a source/drain area 41a, a gate insulating film 43a, and a gate electrode 44a.