A speech recognition method makes it possible to improve the accuracy of recognition of input speech and is capable of operating on a real time basis. This is accomplished by generating from the input speech signal a difference signal which indicates whether the speech power of the input speech is increasing or decreasing for each frame. The similarity between the input speech and a standard pattern is then calculated for each frame, and this is then followed by correcting the similarity calculation on the basis of the generated difference signal and a difference signal relating to the standard pattern obtained from storage. The matching of the input speech and the standard pattern is then effected by using the corrected similarity, and the input speech is then recognized from the result of this matching. Thus, a spectrum matching distance weighted by power information of speech can be obtained in real time.