There is provided a pulse detecting device which resists fluctuations in the quality by locating an ultrasound transmitting piezoelectric element and an ultrasound receiving piezoelectric element with high precision. In the pulse detecting device, a detection sensitivity of the pulse is improved. A transmitting piezoelectric element and a receiving piezoelectric element are fixed onto a substrate by electrodes. The transmitting piezoelectric element is excited in response to an inputted drive voltage signal to generate an ultrasound and transmits the generated ultrasound to a living body. The receiving piezoelectric element receives an echo produced by reflecting the ultrasound transmitted into the living body by a blood flow of the living body and converts it into a voltage signal. A processing arithmetic unit compares the frequency of the ultrasound generated by the transmitting piezoelectric element with that of the echo received in the receiving piezoelectric element to thereby detect a pulse.