A method of manufacturing a semiconductor device comprises the steps of (a) applying a resin member onto a front surface of a semiconductor wafer having an uneven structure on the front surface thereof, and (b) flattening a surface of the resin member by heating the resin member, and in the method, the resin member is formed also on a side surface of the semiconductor wafer. The method further comprises the steps of (c) performing a thinning process for the semiconductor wafer on a back surface thereof after the step (b), and (d) removing the resin member from the semiconductor wafer after the step (c). By the method, it is possible to uniformize the thickness of a semiconductor wafer which is thinned and reduce the number of foreign matters remaining on a surface of the semiconductor wafer.