A device for guiding a nuclear reactor control cluster comprises guide tubes provided in the fuel assemblies, and in the upper internals, a tubular casing having an upper closure with a hole for passing the cluster drive shaft, horizontal guide plates spaced apart along the casing and cut out so as to let the spider pass and to guide the elements of the cluster, and split tubes for guiding individual elements for protecting the elements from the action of the coolant. Openings are provided immediately below the plates at the top of each internal between the guide plates. The guide tubes in a lower portion of the casing are devoid of openings other than to a slit for passage of a spider carrying the cluster.