To provide the manufacturing method of a semiconductor device, where damages to the substrate layer of an electrode can be prevented and the number of processes can be reduced, and to provide a semiconductor device.

A first insulating film 6, having a trench pattern 6a provided with a sidewall 4, is formed on a substrate 1. A metallic material layer 8, which has a recessed part along the inner wall of the trench pattern 6a, is formed. After the inside of the recessed part of the metal material layer 8 is filled with a second insulating film 9, a first insulating film 6 is exposed through planarization. The upper part of the metal material layer 8 in a trench pattern 6a is eliminated, the metallic material layer 8 is dug, and a gate electrode 8a constituted of the metal material layer 8, whose section has a recessed shape is formed in a bottom part of the trench pattern 6a. After a stopper layer 10 is embedded in the trench pattern 6a in the upper part of the gate electrode 8a, the first insulating film 6 and the second insulating film 9 are removed by etching, using the stopper layer 10 and the sidewall 4 as stoppers, and connection holes 12a, 12b which reach the substrate 1 and the gate electrode 8a, respectively, are formed.