A device for forming bales of hay, straw or similar crops includes a container in which there is yieldably mounted a holding member situated between the inlet end and the outlet end of the baling chamber of the container. The device picks crops up from the ground and advances the same into the inlet end of the baling chamber so that the crops form a bale thereat, and the holding member presses against the forming bale for the entire duration of the formation of the bale. The holding member retards the advancement of the forming bale toward the outlet end of the baling chamber and yields only after the material of the forming bale has reached a desired degree of packing. The holding member may be a flap pivoted in the container or a shield mounted on a tiltable frame for movement relative thereto and for tilting therewith. At the beginning of the baling operation, the flap or the shield extend across the baling chamber intermediate the inlet and outlet ends thereof and the flap is gradually pivoted, and the shield gradually shifted, by the advancing forming bale. The pivoting of the flap and the displacement of the shield are controlled either by a hydraulic arrangement or a braking arrangement.