1. An imaging device that combines plural pieces of image data so as to generate image collage data, the imaging device comprising: an imaging unit that images a subject so as to obtain first image data; an image processing unit that performs image processing on the first image data so as to obtain second image data; a first storage unit in which image data including one or both of the first image data and the second image data is stored; an image analysis unit that analyzes a feature of the image data stored in the first storage unit; a scenario generation unit that generates scenario data on the basis of an analysis result of the image analysis unit; a scenario changing unit that performs setting so as to change the scenario data generated by the scenario generation unit; and an image collage processing unit that combines the plural pieces of image data stored in the first storage unit on the basis of the scenario data so as to generate the image collage data, wherein after the scenario generation unit has generated the scenario data on the basis of the analysis result of the image analysis unit, when the scenario changing unit performs setting so as to change the scenario data, the scenario data is prioritized, and when the scenario changing unit does not perform setting so as to change the scenario data, the scenario data is updated on the basis of the analysis result of the image analysis unit, in synchronization with a change in the image data stored in the first storage unit.