A biological information measurement device includes a photoplethysmographic sensor that detects a photoplethysmographic signal, an envelope detection processor that generates an envelope of the photoplethysmographic signal, and an amplitude normalization processor that normalizes amplitude of the photoplethysmographic signal to a desired amplitude value based on amplitude of the envelope. The device further includes an adaptive line spectrum enhancer that is capable of varying a filter coefficient, suppressing an aperiodic component contained in the normalized photoplethysmographic signal, and outputting a periodic component. A biological information obtainment unit is provided to obtain biological information such as a pulse rate based on an output signal from the adaptive line spectrum enhancer.