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 (24, 60) 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 (24, 60); a supporting portion (20b, 40, 52, 66) clamping an outer ring or inner ring of the rolling bearing from both sides to support the rolling bearing; and a damper mechanism (38, 76) 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 (24, 60) 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 (24, 60); a supporting portion (20b, 40, 52, 66) clamping an outer ring or inner ring of the rolling bearing from both sides to support the rolling bearing; and a damper mechanism (38, 76) 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.