1. A learning device comprising: a processor having: a plurality of learning modules, each of which performs update learning to update a plurality of model parameters of a pattern learning model that learns a pattern using input data; model parameter sharing unit causing two or more learning modules from among the plurality of learning modules to share the model parameters; and sharing strength updating unit sharing strengths between the learning modules so as to minimize learning errors when the plurality of model parameters are updated by the update learning, wherein the model parameter sharing unit corrects the model parameters updated by each of the two or more learning modules using a weight average value of the model parameters updated respectively by the two or more learning modules to thereby cause the two or more learning modules to share the model parameters updated respectively by the two or more learning modules.