A method of manufacturing a semiconductor device, includes mounting a semiconductor chip on a wiring substrate such that one surface of the semiconductor chip is faced to one surface of the wiring substrate, and filling a first resin in a gap between the surface of the wiring substrate and the surface of the semiconductor chip such that part of the first resin protrudes from the gap. In the filling of the first resin, the first resin is injected into the gap by use of a first resin injection nozzle while the first resin injection nozzle is being moved along any one of sides of the semiconductor chip or along two sides of the semiconductor chip which are adjacent to each other.