The invention relates to a retaining device (5) for a rotatable center block (17) in an injection molding device (1), comprising a lower rotary plate (14) rotatable about an axis of rotation (13) and driven by a motor (15), the lower rotary plate being used for retaining the rotatable center block (17). The retaining device (5) comprises a lower cross member (7), which is mounted movably in the longitudinal direction (x) on guide rails (9) while supported on a machine bed of the injection molding device by means of first bearing blocks (8). The retaining device (5) can have two bearing blocks (16), by means of which the lower cross member (7) is supported in the circumferential direction relative to lower beams (4) of the injection molding device. For a further increase in efficiency, the center block (17) has a main body made of a material of lower density than a coupling plate (23) operatively connected thereto.