The invention relates to a ball screw, comprising a ball roller screw (1) and screw nut (2), arranged thereon, whereby balls (3) are arranged to endlessly circulate in a ball channel (6) defined by ball tracks (4, 5) on the ball roller screw (1) and the screw nut (2). Said ball channel (6) comprises a load section (7) wound about the ball roller screw (1) the beginning and end of which are endlessly connected by means of a load-free return section (8). A minimum of two and a maximum of four balls (3) are housed in a common ball cage (10, 22), the cage traps (11) of which each house one of the balls (3), whereby the ball cage (10, 22) comprises a disc (12, 15), at the axial end thereof between adjacent balls (3), each engaging in the ball channels (4, 5) and provided on the side thereof facing the balls (3) with a concave housing (14) for the balls (3).