This image forming device 1 comprises a control unit, a connector interface 31, an external memory 33, and an image forming unit. The control unit instructs the output of a predetermined image data. The connector interface 31 is connected to the control unit. The external memory 14 can be removably connected to the connector interface 31 while it stores the output image data. The image forming unit is capable of receiving the instruction from the control unit and delivering onto paper the image data stored in the external memory 14.