An evaluation apparatus evaluates the relationship between multiple subjects in communication between the subjects. A non-verbal information measurement unit measures non-verbal information respectively obtained for the multiple subjects, and quantifies the non-verbal information so as to generate first signals each configured as a time-series signal. A waveform analyzing unit generates second signals for the respective subjects, each configured as a value that relates to a feature configured as non-verbal information rhythm with respect to the corresponding one of the subjects. A relationship evaluation unit generates a third signal configured as an index that represents a mental state with respect to the relationship between the multiple subjects, based on a relative relationship between the multiple second signals that correspond to the respective subjects.