A fault signal detection method includes acquiring decomposition signals according to a frequency band, by decomposing an original signal in the time domain into a certain number of frequency band signals, combining the certain number of decomposition signals and calculating a classification result value for classifying the original signal into a normal signal or a fault signal using a classification model using at least one decomposition signal included in a combination method as input and determining a combination method for detecting a fault signal based on classification result values of the classification model.