An ultrasound transducer that achieves broadband characteristics without degrading the sensitivity of the ultrasound transducer. Piezoelectric element (202) includes piezoelectric thin film (203), first electrode (204) that is disposed on a first surface of piezoelectric thin film (203) in a thickness direction of piezoelectric thin film (203), and second electrode (205) that is disposed on a second surface of piezoelectric thin film (203) in the thickness direction of piezoelectric thin film (203), and at least two of parameters of a spring constant, a viscosity coefficient, and a mass in an equivalent single damped oscillation model representing a structure of a diaphragm composed of each piezoelectric cell (200) are each set to a value that is different among the piezoelectric cells (200) such that a relationship between a driving frequency ratio and a phase in the diaphragm is substantially identical among the piezoelectric cells (200).
