[Problem] To provide a learning device, a learning program, an abnormality detection device, and an abnormality detection program that enable prevention of a decrease in the accuracy of reproduction of a normal image even when variation of the normal image is based on a distribution other than a normal distribution. [Solution] The learning device comprises a data acquisition unit 210, an encoder unit 221, a noise addition unit 230, a decoder unit 223, and a learning unit 240. The data acquisition unit 210 acquires training data comprising normal data to be inspected. The encoder unit 221 extracts a feature amount of the training data. The noise addition unit 230 adds noise to the feature amount. The decoder unit 223 restores the training data from the feature amount with the added noise. The learning unit 240 updates parameters of the encoder unit 221 and the decoder unit 223 on the basis of the training data and the restored data restored by the decoder unit 223.