Abstract: The present invention relates to a cutting device for cutting straw and similar material into pieces, of the type which comprises a driven shaft (11) kept in a housing (21), where said shaft (11) is provided with longitudinally proceeding rows (1-6) of knife attachments for knives (15), which extends radially from the shaft and are provided with cutting edges. Said knives (15), under operation pass between a row of counter knives (19) directed towards said shaft and preferably provided with cutting edges in the same way, whereby the straw material to be cut is fed towards said counter arms (9). The number of rows (1, 2, 3, 4, 5, 6) with knife attachment (14) are at least six. The distances between three knife attachments in a longitudinally proceeding row, have a proportion of 4:4:5 of a repeating unit, where the arms (4,5) in a rotation round at least forms two screw lines.