A biometric information sensor includes a flexible substrate, an adhesive, a heartbeat signal detector, an electrocardiographic signal detector, a pulse wave detector, and a signal processor. The signal processor calculates an electrocardiographic peak estimated value resulting from estimating the wave of an electrocardiographic signal detected by the electrocardiographic signal detector from a heartbeat signal detected by the heartbeat signal detector based on the heartbeat signal and the electrocardiographic signal. The signal processor estimates a pulse wave transmit time based on the calculated electrocardiographic peak estimated value a photoplethysmographic signal detected by the pulse wave detector.
