To provide a manufacturing method of a semiconductor device for effectively injecting indium into a process for mounting different gate insulating film thicknesses.

This manufacturing method of a semiconductor device for mounting a plurality of different gate insulating film thicknesses and at the same time, forming an N-channel region using indium at a specific region of a MOSFET includes a process for forming a P-well region and a first N-channel region, consisting of constituents other than indium, a process for forming a first gate insulating fil, a process for removing the first gate insulating film at a prescribed region other than the first N-channel region, a process for forming the P-well region, in a region where the first gate insulating film has been removed, and a second N-channel region containing indium, and a process for forming a second gate insulating film on the surface of the second N-channel region.