Ultrasonic transducer is the sensor which is measuring distance. Piezo ceramic of ultrasonic sensor and adhesive technique of matching layer are the most core techniques. With the study of relation on matching layer which takes off the ultrasonic wave into the air, this paper aims to find the second useful frequency as the results which can be changed are extracted in case piezo ceramic and matching layer are bonded. And the experiment is done with piezo ceramic as real piezoelectric element and matching layer of chemical wood. OD of piezo ceramic has designed by  × and OD of matching layer is designed by × with   . Acoustic impedance is generated at the most optimum resonant frequency of 53 Khz. As experimental result, more available frequency can be generated by using the adhesive close to solid than the flexible one.