Both controlling damage when assembling an ultrasonic probe using a chip formed with a capacitive ultrasonic transducer and securing operational reliability are achieved. In a semiconductor substrate on which the capacitive ultrasonic transducer (CMUT) is formed on a first primary surface, a protective film is formed on the surface of the ultrasonic transducer which is formed on the first primary surface of the semiconductor substrate which is then thinned by polishing a second primary surface opposite to the first primary surface of the semiconductor substrate, an ultrasonic transducer chip is cutout of the semiconductor substrate, a sound absorbing material is provided on the surface opposite to the surface formed with the ultrasonic transducer, and the protective film formed on the surface of the ultrasonic transducer is removed.