A piezoelectric element driving circuit includes a boosting circuit, a driving circuit, a waveform shaping circuit, and a computing circuit. The driving circuit includes a differential amplifier circuit with an LPF, an amplifier circuit with a BPF, an inverter, a resistor, and a comparator. The driving circuit applies a driving signal to a piezoelectric element of a piezoelectric pump. The waveform shaping circuit extracts a voltage signal from the driving circuit. On the basis of the voltage signal, the waveform shaping circuit and the computing circuit determine a voltage value corresponding to driving current flowing through the piezoelectric element. The computing circuit outputs a control signal to the boosting circuit on the basis of the voltage value. The boosting circuit sets the value of a DC supply voltage on the basis of the control signal, and outputs the DC supply voltage.