1. A pressing detector, comprising:a piezoelectric element configured to generate an electric charge based on an amount of displacement of an operation surface;
a displacement detection element configured to generate an output value based on the amount of the displacement of the operation surface; and
a pressing detection unit configured to:
calculate an integrated value of a voltage generated by the electric charge generated by the piezoelectric element,
intermittently operate the displacement detection element, and
correct the calculated and integrated value of the voltage based on the output value generated by the displacement detection element.