The present invention provides a supercharger with an electric motor having improved cooling performance for bearings, in the case of employing a grease lubrication system as a lubrication system of the bearings.A supercharger with an electric motor includes: a rotary shaft; a compressor wheel; a compressor housing for housing the compressor wheel; an electric motor including a motor rotor and a motor stator, and giving rotation force to the rotary shaft; a motor housing, for housing the electric motor; a first grease-sealed bearing for rotatably supporting the rotary shaft; and a bearing housing for housing the first grease-sealed bearing, and disposed between the compressor housing and the motor housing. Inside the bearing housing, a cooling passage through which a cooling medium flows is provided in a circumferential direction on an outer circumferential side of the first grease-sealed bearing.