To rapidly and surely perform an abnormality detection, for example, for a small furnace by providing a specific information detection method and device capable of extremely rapidly and surely detecting specific information contained in an information signal from an object of detection.

This device comprises a wavelet analysis part 11 for decomposing the information signal from the object of detection by use of wavelet analysis method, thereby extracting a feature including abnormality information; and an AANN simulation part 14 for inputting the extraction result to an auto associative neural network learnt by an AANN learning part 13, thereby further extracting the abnormality information from the feature.