An Out-Of-Distribution (OOD) detection method performed by an OOD detection device is provided. The OOD detection method includes generating a noise filter using training data based on a target distribution and using a classification model pre-trained according to the target distribution, training the generated noise filter to reduce a loss function for a first output value obtained by applying the training data passed through the generated noise filter to the pre-trained classification model, and detecting Out-Of-Distribution (OOD) for new data using a second output value obtained by applying the new data passed through the trained noise filter to the pre-trained classification model.