There is provided an image generation apparatus used for a vehicle having side mirrors. An image acquisition unit is configured to acquire a plurality of captured images obtained by a plurality of cameras including side cameras provided in the side mirrors. A generation unit is configured to generate a composite image which indicates a periphery of the vehicle viewed from a virtual viewpoint, by using target areas defined for the respective captured images. A state acquisition unit is configured to acquire a developed or folded state of the side mirrors. The generation unit changes the target areas in accordance with the developed or folded state of the side mirrors.