A piezoelectric transformer includes a molded package having first and second inner walls facing each other, a plurality of pairs of projections provided on the first and second inner walls, and a piezoelectric transformer element mechanically supported by the projections so that the piezoelectric transformer element is accommodated in an internal space defined by inner walls of the molded package but separated from the inner walls of the molded package. As a result, the thickness of the package can be reduced.