PURPOSE:To provide a compact, high-performance piezoelectric transformer by laminating elements whose polarization direction is inverted as prearranged in a piezoelectric element with a drive electrode and a power generation electrode provided on a piezoelectric ceramic plate which is polarized in a longitudinal direction. CONSTITUTION:Drive electrodes 32, 33 are formed on one end of the upper and lower surfaces of a piezoelectric ceramic plate 31 polarized in a thickness direction to form a low impedance part. Then said electrodes are polarized in a longitudinal direction to form a power generation electrode 34 on the other end surface and also to form a vertical effect high impedance part so that a piezoelectric transformer element a which vertically oscillates in a longitudinal direction. At the same time, an element b whose polarization direction lengthwise is opposite to that of the element a is formed. Then the element a is laminated in such manner that the polarization direction of the drive part is inverted and laminated, thus making an element group A while in the same way, an element group B is made. These two element groups are overlapped and bonded into a single form, utilizing a folded oscillation mode. Thus it is possible to obtain a small-size piezoelectric transformer capable of displaying a sufficient function within a low cycle range of several kHz to sereral 10kHz.