To provide a rolling reduction apparatus for cast slabs, which apparatus can carry out the rolling reduction while adjusting the carrying speed of the cast slabs for every strand arranged at the same position in a plurality of the strands in continuous casting facilities.

The rolling reduction apparatus 10 for the cast slabs in the continuous casting facilities includes rolling reduction means 19 to 21 having a pair of upper and lower rolling rolls 17, 18 for carrying out the rolling reduction of the cast slabs 14 to 16, and speed reducers 22, 24 to be connected to a pair of the upper and lower rolling rolls 17, 18 via output shafts 40, 47 thereof in the respective strands 11 to 13. The speed reducers 22, 24 to be arranged in a plurality of the strands 11 to 13 have a main driving shaft 23 to be connected to a driving motor 35 as their rotation input source, and the speed reducer except one of a plurality of the speed reducers 22, 24 is a differential planetary speed reducer having a speed adjusting input shaft 49. The speed of a pair of the upper and lower rolling rolls 17, 18 of a plurality of the rolling reduction rolling means 19 to 21 can be individually adjusted.