The present invention concerns a Magnus rotor comprising a carrier arranged in the interior of the Magnus rotor, a rotor which in operation of the Magnus rotor rotates about the carrier, a bearing which carries the rotor on the carrier and a heating device provided for producing heated air in the interior of the carrier. The carrier has at least one opening at its outside, which connects the internal space in the carrier to the intermediate space between the carrier and the rotor in such a way that air can pass through between those two spaces.