Disclosed are a speech recognition method and a speech recognition device, in which speech recognition is performed by executing an artificial intelligence (AI) algorithm and/or a machine learning algorithm provided therein. According to an embodiment of the present disclosure, the speech recognition method includes buffering an inputted spoken utterance, determining whether a preset wake-up word is present in the spoken utterance by comparing the buffered spoken utterance to the preset wake-up word, and in response to the preset wake-up word in the spoken utterance, activating a speech recognition function and isolating, from the spoken utterance, a spoken sentence as a voice command without the wake-up word, and processing the spoken sentence and outputting a processing result.