A pneumatic single-grain sowing machine includes: a closed housing； a rotatably driven separating device, which has circularly arranged perforations； and a fan for producing a pressure difference between the housing and the interior of the separating device, the separating device thus being designed to separate seed by use of the perforations with the aid of the pressure difference, the separating device being designed as a closed hollow drum having two side walls arranged at a distance from each other. The separating device is designed to compensate slight housing expansions.
