An image processing device includes: an image sensor; a data buffer; an imaging interface part configured to read image data from the image sensor, generate an imaging signal, and write the generated imaging signal to the data buffer; an imaging processor configured to read out the imaging signal written in the data buffer and perform image processing; a synchronization signal generator configured to generate a synchronization signal synchronized with the image sensor; and a clock frequency controller configured to control a clock frequency of a clock input to the imaging processor on the basis of the synchronization signal, wherein the clock frequency controller is configured to change the clock frequency after a start of a valid period of the synchronization signal.