A rotor holder for an injection moulding die for producing a connection of a shaft to a laminated rotor core, which defines a through hole along its axis of rotation for receiving the shaft, wherein the rotor holder has two holding sections (10A, 10B), wherein at least one of the holding sections (10A, 10B) has a free end with a radially outer first mating surface, which is configured to correspond to an inner surface of the laminated rotor core, wherein at least one of the holding sections (10A, 10B) is configured to be inserted into the laminated rotor core concentrically to the axis of rotation and to hold the laminated rotor core via the first mating surface concentrically to the axis of rotation, wherein at least one of the holding sections (10A, 10B) forms a receiving space for receiving the shaft and has a radially inner second mating surface in the receiving space, which is configured to correspond to an outer surface of the shaft, wherein at least one of the holding sections (10A, 10B) is configured to hold the shaft on the second mating surface concentrically to the axis of rotation and to hold itself extending at least partially into the laminated rotor core, wherein at least one of the holding sections (10A, 10B) is configured to partially close the through hole passing through the laminated rotor core and to delimit a cavity formed in the laminated rotor core by the through hole, characterised in that a first holding section of the two holding sections (10A, 10B) is configured to be insertable into the laminated rotor core from a first side along the axis of rotation, and a second holding section of the two holding sections (10A, 10B) is configured to be insertable into the laminated rotor core from an opposite second side along the axis of rotation, and wherein the first holding section and the second holding section are each formed as a sleeve arrangeable in the injection moulding die (2, 3), or the first holding section is formed integrally and in one piece with the injection moulding die (2, 3) and the second holding section is formed as a sleeve arrangeable in the injection moulding die (2, 3). wherein the rotor holder has two holding sections (10A, 10B), wherein at least one of the holding sections (10A, 10B) has a free end with a radially outer first mating surface, which is configured to correspond to an inner surface of the laminated rotor core, wherein at least one of the holding sections (10A, 10B) is configured to be inserted into the laminated rotor core concentrically to the axis of rotation and to hold the laminated rotor core via the first mating surface concentrically to the axis of rotation, wherein at least one of the holding sections (10A, 10B) forms a receiving space for receiving the shaft and has a radially inner second mating surface in the receiving space, which is configured to correspond to an outer surface of the shaft, wherein at least one of the holding sections (10A, 10B) is configured to hold the shaft on the second mating surface concentrically to the axis of rotation and to hold itself extending at least partially into the laminated rotor core, wherein at least one of the holding sections (10A, 10B) is configured to partially close the through hole passing through the laminated rotor core and to delimit a cavity formed in the laminated rotor core by the through hole, characterised in that a first holding section of the two holding sections (10A, 10B) is configured to be insertable into the laminated rotor core from a first side along the axis of rotation, and a second holding section of the two holding sections (10A, 10B) is configured to be insertable into the laminated rotor core from an opposite second side along the axis of rotation, and wherein the first holding section and the second holding section are each formed as a sleeve arrangeable in the injection moulding die (2, 3), or the first holding section is formed integrally and in one piece with the injection moulding die (2, 3) and the second holding section is formed as a sleeve arrangeable in the injection moulding die (2, 3).