Disclosed are a speech recognition device and a speech recognition method, which perform speech recognition by executing an artificial intelligence (AI) algorithm and/or a machine learning algorithm provided therein, and which can communicate with other electronic devices and an external server in a 5G communication environment. According to an embodiment, the speech recognition method includes setting an additional wake-up word target capable of activating a speech recognition function in addition to a preset wake-up word, generating a plurality of additional wake-up word utterances formed on the basis of the additional wake-up word target being uttered under various conditions, learning a wake-up word recognition algorithm by using each of the spoken utterances of the additional wake-up word to generate an additional wake-up word recognition algorithm, and executing the additional wake-up word recognition algorithm upon receiving a select word uttered by a user to determine whether to activate the speech recognition function.