The present invention provides a method for manufacturing a semiconductor device, which is capable of suppressing an overflow of a sealing resin and obtaining good sealing quality, simply and at low cost. Further, the present invention provides a semiconductor device that suppresses an overflow of a sealing resin and has good sealing quality, simply and at low cost. Liquid first underfill higher in viscosity than liquid second underfill is charged into space defined between a corresponding edge side of four edge sides of each of semiconductor chips, at which the distance between at least one edge side and each of pads opposite thereto, of an interposer is of the shortest, and the interposer. The liquid first underfill is cured and sealed with first underfill. Thereafter, the liquid secondunderfill is charged into space defined between the semiconductor chip and the interposer excluding the space sealed with the first underfill. The liquid second underfill is cured and sealed with second underfill.