A method of producing a semiconductor device including and packaging a semiconductor forming an electronic circuit therein and adapted for mounting on a board, comprising the steps of: - forming an insulation layer by stacking a plurality of resin layers (20, 21, 22, 23) on a surface of a semiconductor wafer excluding a scribe line, wherein the plurality of resin layers are formed so that, as they get farther from the semiconductor wafer, their areas become gradually smaller from an area of an upper surface of the semiconductor wafer, and a side surface and an upper surface of each of the resin layers and the upper surface of the substrate form a stepwise shape; - forming a wiring layer (30, 31, 32, 33, 34, 35) electrically connected to the electronic circuit and buried in the insulation layer; - forming a conductive post electrically connected to the wiring layer on the insulation layer; - forming an insulating buffer layer, buffering a stress which is generated when the semiconductor device is mounted on the board, on a region excluding a region having a width of 20 μm or more at an outer circumferential portion of an uppermost resin layer of the insulation layer, the step of forming the insulating buffer layer comprises the steps of: - aligning a printing mask with a semiconductor wafer of the semiconductor device so that the printing mask is arranged along the scribe line and made to contact on the width which is 20 μm or more from the outer circumference of the uppermost resin layer, wherein the printing mask has the configuration of combining a mesh screen having a thickness of 10 μm or less and a metal mask having a thickness equivalent to that of the buffer layer, the metal mask being configured by a plurality of first metal masks spreading in a first direction and a plurality of second metal masks spreading in the orthogonal direction thereto; and - printing the buffer layer by using the printing mask; and - dicing the wafer on the scribe line. - forming an insulation layer by stacking a plurality of resin layers (20, 21, 22, 23) on a surface of a semiconductor wafer excluding a scribe line, wherein the plurality of resin layers are formed so that, as they get farther from the semiconductor wafer, their areas become gradually smaller from an area of an upper surface of the semiconductor wafer, and a side surface and an upper surface of each of the resin layers and the upper surface of the substrate form a stepwise shape; - forming a wiring layer (30, 31, 32, 33, 34, 35) electrically connected to the electronic circuit and buried in the insulation layer; - forming a conductive post electrically connected to the wiring layer on the insulation layer; - forming an insulating buffer layer, buffering a stress which is generated when the semiconductor device is mounted on the board, on a region excluding a region having a width of 20 μm or more at an outer circumferential portion of an uppermost resin layer of the insulation layer, the step of forming the insulating buffer layer comprises the steps of: - aligning a printing mask with a semiconductor wafer of the semiconductor device so that the printing mask is arranged along the scribe line and made to contact on the width which is 20 μm or more from the outer circumference of the uppermost resin layer, wherein the printing mask has the configuration of combining a mesh screen having a thickness of 10 μm or less and a metal mask having a thickness equivalent to that of the buffer layer, the metal mask being configured by a plurality of first metal masks spreading in a first direction and a plurality of second metal masks spreading in the orthogonal direction thereto; and - printing the buffer layer by using the printing mask; and - dicing the wafer on the scribe line. - aligning a printing mask with a semiconductor wafer of the semiconductor device so that the printing mask is arranged along the scribe line and made to contact on the width which is 20 μm or more from the outer circumference of the uppermost resin layer, wherein the printing mask has the configuration of combining a mesh screen having a thickness of 10 μm or less and a metal mask having a thickness equivalent to that of the buffer layer, the metal mask being configured by a plurality of first metal masks spreading in a first direction and a plurality of second metal masks spreading in the orthogonal direction thereto; and - printing the buffer layer by using the printing mask; and - dicing the wafer on the scribe line.