To enable image data to be transmitted and received in an efficient manner by making effective use of relatively narrow band communications circuits in image data reception devices, an image data management device transmits image data stored in the auxiliary storage section to a plurality of printing control devices connected thereto via the Internet. In this image management device, when transmitting image data, a transmission instruction registering section registers a transmission instruction including a transmission destination, transmission instruction timing, transmission priority, and the like, is registered in the transmission instruction table, and a transmission image data setting section sets a transmission order for the image data for each transmission destination, on the basis of the timing at which transmission was instructed, and the transmission priority, and a plurality of image data corresponding to a plurality of transmission destinations are transmitted in parallel according to the set transmission order for each transmission destination.