A method of manufacturing a semiconductor device includes forming a first via having a first diameter in a first main surface of a semiconductor substrate having a first thickness, after forming a first insulating film on a bottom surface and a side surface of the first via, forming a first through electrode inside the first via a first barrier metal film, after forming the first through electrode, processing the semiconductor substrate from a second main surface on an opposite side of the first main surface to reduce the first thickness of the semiconductor substrate to a second thickness thinner than the first thickness, after processing the semiconductor substrate, forming a third insulating film on the second main surface of the semiconductor substrate, and after forming the third insulating film, sequentially processing the third insulating film and the semiconductor substrate.