A learning device includes one or more processors. The processors acquire input data and a target label indicating a correct answer of inference based on the input data. The processors add noise to at least one of the input data and intermediate layer data of the neural network and perform inference by the neural network with respect to the input data. The noise is based on contributions of a plurality of elements included in the input data with respect to an inference result when the input data is input to a neural network. The processors update parameters of the neural network so that the inference result by the neural network matches the target label.