CLEANING DEVICE, IMAGING UNIT WITH CLEANING DEVICE, AND CLEANING METHOD

In the cleaning device of the present invention, a signal processing circuit (20) determines that a foreign substance has adhered to a surface of a protection cover (2) based on at least two pieces of information among a change amount of a resonant frequency (Δf) when a vibration portion (12) is driven at a first voltage (V1), a change amount of a current value (ΔI) relating to an impedance detected by an impedance detection unit (70), and a temporal change (brightness integral value) of an image captured by an imaging portion (5), and cleans the surface of the protection cover (2) by controlling the vibration portion (12) in accordance with the determination.