A CPU acquires factor information for a degree of arteriosclerosis, stores a plurality of pseudo blood flow waveforms, generates a waveform estimated as a blood flow waveform by compositing the plurality of pseudo blood flow waveforms based on the factor information, decomposes a pulse waveform into waveforms of an ejected wave and a reflected wave using the pulse waveform and the waveform estimated as the blood flow waveform, and calculates an index of the degree of arteriosclerosis from a relationship between the ejected wave and the reflected wave obtained by decomposing the pulse waveform.
