An image processing device includes a controller. The controller is configured to perform: acquiring image data having a plurality of objects; calculating an amount of characteristic of each of the objects, the amount of characteristic indicating a degree of change in pixel values; setting a process order based on the amount of the characteristic of each of the objects; setting a target value, the target value being a reference value to reduce a data size of the image data; reducing an object data size of at least one of the plurality of objects based on the process order in such a way that the data size of the image data becomes smaller than or equal to the target value, thereby generating a reduced object; and generating reduced image data having a data size smaller than the data size of the image data by using the reduced object.