A sensor part has sensor cells provided in a matrix arrangement on a sensor that detects a pulse within a region in which the pulse of a diagnostic target is detected, in a state in which a pressure is applied to the region through the sensor. A diagnostic apparatus acquires a distribution of a pulse waveform based on the pulse detected in a state in which the pressure is constant, determines observation positions within the region, and determines a maximum amplitude at the observation positions that are determined by increasing the pressure, based on the distribution of the pulse waveform. A digitized score of the pulse at each observation position is computed based on the pressure at a time when the pulse waveform having the maximum amplitude is obtained at each observation position.
