An electric supercharger comprising: a compressor wheel housed in a compressor housing ; an electric motor for driving a rotation shaft of the compressor wheel; a motor inverter for controlling rotation speed of the rotation shaft, the motor inverter being arranged adjacent to the electric motor in series on the rotation shaft; a rolling bearing provided on each side of the electric motor to rotatably support the rotation shaft ; a sleeve provided outside the rolling bearing and a gap (Si) formed between the sleeve and the rolling bearing ; a supporting portion clamping an outer ring or inner ring of the rolling bearing from both sides to support the rolling bearing; and a damper mechanism arranged outside the sleeve to elastically support the sleeve , characterized in that the rolling bearing arranged on a motor inverter side comprises a damper sleeve structure , the damper sleeve structure comprising: a large diameter sleeve having an inward engagement portion which projects inwardly at one end; a cylindrical spring guide provided inside the large diameter sleeve and having an outward engagement portion which projects outward at one end; the rolling bearing arranged inside the large diameter sleeve , the gap (Si) being formed between the large diameter sleeve and the rolling bearing ; and a spring member arranged in a cylindrical space formed between the large diameter sleeve and the spring guide to impart an elastic clamping force to the rolling bearing via the outward engagement portion , the spring member being clamped between the rolling bearing and the inward engagement portion . a compressor wheel housed in a compressor housing ; an electric motor for driving a rotation shaft of the compressor wheel; a motor inverter for controlling rotation speed of the rotation shaft, the motor inverter being arranged adjacent to the electric motor in series on the rotation shaft; a rolling bearing provided on each side of the electric motor to rotatably support the rotation shaft ; a sleeve provided outside the rolling bearing and a gap (Si) formed between the sleeve and the rolling bearing ; a supporting portion clamping an outer ring or inner ring of the rolling bearing from both sides to support the rolling bearing; and a damper mechanism arranged outside the sleeve to elastically support the sleeve , characterized in that the rolling bearing arranged on a motor inverter side comprises a damper sleeve structure , the damper sleeve structure comprising: a large diameter sleeve having an inward engagement portion which projects inwardly at one end; a cylindrical spring guide provided inside the large diameter sleeve and having an outward engagement portion which projects outward at one end; the rolling bearing arranged inside the large diameter sleeve , the gap (Si) being formed between the large diameter sleeve and the rolling bearing ; and a large diameter sleeve having an inward engagement portion which projects inwardly at one end; a cylindrical spring guide provided inside the large diameter sleeve and having an outward engagement portion which projects outward at one end; the rolling bearing arranged inside the large diameter sleeve , the gap (Si) being formed between the large diameter sleeve and the rolling bearing ; and a spring member arranged in a cylindrical space formed between the large diameter sleeve and the spring guide to impart an elastic clamping force to the rolling bearing via the outward engagement portion , the spring member being clamped between the rolling bearing and the inward engagement portion . <EOS>