An image processing device causing a projection unit to project an image includes: a detection unit that detects an operation mode of the image processing device; and a projection control unit that causes the projection unit to project a menu image with brightness corresponding to the operation mode detected by the detection unit so that, if the operation mode detected by the detection unit is a first operation mode in which alignment of projection regions of a plurality of projection units is performed for a multi-screen display, of the menu image projected by the projection unit, a portion corresponding to an overlapping region where the projection regions of the plurality of projection units overlap each other in the multi-screen display is made brighter than the portion in a case where the operation mode detected by the detection unit is a second operation mode in which the alignment has been completed.