An active learning system samples known data, and learns the known data independently in a plurality of learning machines, and selects data to be next learned for unknown data. The active learning system comprises a sampling weighting device for weighting the known data when they are sampled, a prediction weighting device for weighting the learning results of the learning machines when they are integrated, and a data weighting device for weighting the learning results when the data to be next learned is selected. When an extreme deviation is present in the count of data, each of the weighting devices more heavily weights a larger count of data.