1. An image processing device which performs a process of rendering an image in a single frame by allocating an object to be displayed as an image to any of a plurality of layers and superimposing the plurality of layers, wherein the image processing device refers to an object database including a list of object rendering commands for each layer and dynamically changes the number of object rendering processes performed in each layer according to the number of rendering commands included in the list, when rendering an image in a single frame; wherein a rendering command is rewritten to a command obtained by adding up a rendering command that is already registered and an additional rendering command, when the additional rendering command is output to an object that is subjected to the rendering command that is already registered in the list included in the object database.