Light is irradiated to a finger of a subject and received from the finger of the subject to extract a pulse wave signal, generates an optimized pulse wave signal in a desired type by sampling the extracted pulse wave signal according to a predetermined sampling condition and normalizes the generated pulse wave signal, the entire segment of the normalized pulse signal is divided into a plurality of window segments to detect a pulse wave amplitude value with respect to a pulse wave signal for each window, a first eigenvector for each subject corresponding to a pulse wave amplitude value of the entire window segment is extracted by using a linear discriminant analysis and then the first eigenvector per subject is compared with a threshold, determines distribution of eigenvectors for each subject compared to the threshold and thus a characteristic of the corresponding subject is diagnosed.