A method of manufacturing a semiconductor device includes: preparing a semiconductor wafer; forming a conductive portion by forming holes in an active surface, forming an insulating film, and embedding a conductive material; forming a first groove; bonding the semiconductor water and a support body via an adhesive layer; thinning the semiconductor wafer by grinding a rear surface while maintaining the insulating film not exposed; forming a second groove; separating each of the semiconductor element sections to make a plurality of semiconductor chips, by isotropic etching so as to expose the insulating film; exposing the conductive portion from the insulating film by etching from the rear surface, to form feedthrough electrodes; and separating the semiconductor element sections into individual pieces by peeling semiconductor chips off from the support body.