To obtain a learning device of the number of passes in a reversing rolling mill with which the number of good passes can be set quickly in accordance with the change of rolling conditions.

This learning device is provided with a calculating device 6 for calculating a pass schedule, a data gathering device 7 for gathering the actual value of the number of the passes until a desired thickness is obtained and a learning device 8 of the number of the passes for learning the number of the passes on the basis of the preset value of the number of the passes set in the calculating device and the actual value of the number of the passes gathered by the data gathering device. The learning device 8 of the number of the passes is provided with a judging means 9 of the learning of the number of the passes which judges whether to learn the number of the passes or not on the basis of the preset value of the number of the passes and the the actual value of the number of the passes, a storing means 11 of the learned value of the number of the passes for storing the learned value of the number of the passes and an updating means 10 of the learned value of the number of the passes for updating the learned value of the number of the passes stored in the storing means of the learned value of the number of the passes by calculating the learned value of the number of the passes when judging that the pass is one to be learned by the judging means of the learning of the number of the passes.