Printing processing is carried out efficiently when a print order regarding image data is placed through a network. Order information C and thumbnail image data sets TS of image data sets S to be printed are sent from a user terminal 11 to an order reception server 21 in a DPE store 2. A controller 23 judges whether or not a communication line of a network 3 and/or a digital mini-laboratory 22 are heavily loaded, and sends a reception permit Q to the user terminal 11 if a result of the judgment is negative. The user terminal 11 receives the reception permit Q and accesses the order reception server 21 to send the image data sets S thereto. The digital mini-laboratory 22 carries out printing processing on the image data sets S to generate prints P.