In a speech recognition device according to one embodiment, a microphone detects sound and generates an audio signal corresponding to the sound, an adjustment processor adjusts a threshold to be a value less than a first volume level of first input audio signal generated by the microphone, and registers the adjusted threshold, a recognition processor reads the registered threshold, compares the registered threshold with a second input audio signal, discards the second input audio signal when a second volume level of the second input audio signal is less than the registered threshold, and performs a recognition process as the audio signal of a user to be recognized when the second volume level of the second input audio signal is greater than or equal to the registered threshold.