Compressor and electrical drive machine for this compressor, wherein the compressor has a compressor wheel, the electrical drive machine comprising at least one stator, wherein the stator has at least one polyphase drive winding for generating a drive magnetic field, and at least one rotor, wherein the rotor has at least one rotor shaft and at least one permanent magnet, wherein the rotor shaft is designed to be attached to a shaft of the compressor, wherein the shaft of the compressor is connected to the rotor shaft by a screw connection, and the rotor shaft has at least one first section and at least one second section, wherein the second section axially adjoins the first section, wherein the second section concentrically surrounds the rotor shaft and is connected to the first section by way of a cone connection, wherein the second section is of hollow design and adjoins one end of the rotor shaft and this end faces the compressor wheel when the rotor shaft is in the attached state and the shaft of the compressor is connected to the first section of the rotor shaft by the screw connection, characterized in that the rotor is attached to the shaft by way of the rotor shaft being screwed onto the shaft by means of an internal thread, wherein the second section comprises a first subsection and at least one second subsection, wherein the first subsection has a first mean diameter and the second subsection has a second mean diameter, wherein the second mean diameter is greater than the first mean diameter, as a result of which a conical bore is formed on the second section, wherein the cone connection comprises a pair of elements, wherein the pair of elements is formed from the conical bore of the second section and a conical outer contour of a projection, which engages into the conical bore, on the compressor wheel, wherein the end bears against the compressor wheel when the rotor shaft is in the attached state. the electrical drive machine comprising at least one stator, wherein the stator has at least one polyphase drive winding for generating a drive magnetic field, and at least one rotor, wherein the rotor has at least one rotor shaft and at least one permanent magnet, wherein the rotor shaft is designed to be attached to a shaft of the compressor, wherein the shaft of the compressor is connected to the rotor shaft by a screw connection, and the rotor shaft has at least one first section and at least one second section, wherein the second section axially adjoins the first section, wherein the second section concentrically surrounds the rotor shaft and is connected to the first section by way of a cone connection, wherein the second section is of hollow design and adjoins one end of the rotor shaft and this end faces the compressor wheel when the rotor shaft is in the attached state and the shaft of the compressor is connected to the first section of the rotor shaft by the screw connection, characterized in that the rotor is attached to the shaft by way of the rotor shaft being screwed onto the shaft by means of an internal thread, wherein the second section comprises a first subsection and at least one second subsection, wherein the first subsection has a first mean diameter and the second subsection has a second mean diameter, wherein the second mean diameter is greater than the first mean diameter, as a result of which a conical bore is formed on the second section, wherein the cone connection comprises a pair of elements, wherein the pair of elements is formed from the conical bore of the second section and a conical outer contour of a projection, which engages into the conical bore, on the compressor wheel, wherein the end bears against the compressor wheel when the rotor shaft is in the attached state.