According to one embodiment, a transducer includes a first electrode, a second electrode, a third electrode, a first piezoelectric portion, and a second piezoelectric portion. A resistor and an inductor are connected to the second electrode. The first piezoelectric portion is provided between the first electrode and the third electrode. The second piezoelectric portion is provided between the second electrode and the third electrode. A ratio of the absolute value of a difference between a first resonant frequency and a second resonant frequency to the first resonant frequency is 0.29 or less. The first resonant frequency is mechanical. The first resonant frequency is of the first piezoelectric portion and the second piezoelectric portion. The second resonant frequency is of a parallel resonant circuit. The parallel resonant circuit includes an electrostatic capacitance, the inductor, and the resistor. The electrostatic capacitance is between the second electrode and the third electrode.