Abstract: The object of the present invention is to realize the piezoelectric ceramics which, even when used as high frequency elements utilizing third harmonics wave of thickness longitudinal vibration, are small in temperature coefficient of resonant frequency and high in mechanical Q value and easy to correspond to the trend toward miniaturization and low voltage driving. When the piezoelectric ceramics with lead titanate as its main component are manufactured in order to achieve this object, it was decided that the piezoelectric ceramics be manufactured by the manufacturing method, wherein a heat treatment is performed between a firing process and a polarization process in the atmosphere of oxygen partial pressure less than the oxygen partial pressure of the atmospheric pressure at temperatures more than 500.degree. C. and not more than the firing temperatures.