The invention refers to a bale forming apparatus (1) with several bale forming rollers (10.1, …, 11.6, 23.1, …, 24.2, 8.1, 8.2) and to a bale forming method by using such a bale forming apparatus(1). A bale forming chamber (12) is positioned between a first set (10) and a second set (11) of bale forming rollers (10.1, …, 11.6). At least one bale forming roller (10.1, …, 10.5) of the first set (10) can move perpendicular to its rotating axis, thereby changing the size of the bale forming chamber (12). A connecting slide (16) can be moved along the sequence of rollers (10.1, …, 10.6) of the first set (10). In every sliding position the connecting slide (16) connects one roller of the first set (10) with one roller of the second set (11).