Identification and clustering of similar acoustic emission (AE) events are important to determine source locations precisely and to evaluate subsurface cracks. An AE cluster analysis method using phase-only correlation (POC) is proposed to identify and hierarchically classify similar AE waveforms. The POC of time-varying spectral representations is used to evaluate the similarity between two waveform images in the time–frequency domain, and cluster analysis is used to classify the waveforms into groups according to a distance measure. The method is applied to waveforms from local earthquakes in Japan to assess its ability to identify similar waveforms perturbed by white noise.