An inhaler includes an atomizing unit including a piezoelectric element substrate having a first IDT including a pair of interlocking comb-shaped electrodes. The atomizing unit is configured to atomize liquid by a surface acoustic wave generated by applying a high-frequency voltage to the pair of interlocking comb-shaped electrodes, and a controller is configured to monitor a resonant frequency of the pair of interlocking comb-shaped electrodes and apply a voltage to the pair of interlocking comb-shaped electrodes at a frequency determined based on the monitored resonant frequency.