A piezoelectric element having a crystal structure that enables a piezoelectric film to be formed in an unstressed state is provided. The piezoelectric film contains an a-axis oriented crystal and a c-axis oriented crystal, where a difference in lattice constant between the a-axis oriented crystal and the c-axis oriented crystal is not more than 0.06 Å. The present inventors have newly found that a stress accumulated in the piezoelectric film can be reduced while maintaining favorable piezoelectric properties when a condition that the difference in lattice constant between the a-axis oriented crystal and the c-axis oriented crystal is not more than 0.06 Å is satisfied. When the condition is satisfied, the c-axis oriented crystal and the a-axis oriented crystal are properly balanced and as a result crystal particles of the piezoelectric film are closest-packed on its base in an ideal state, which contributes to a reduced stress.