There is provided an image forming system, comprising an image forming device and an information processing device communicatably connected to the image forming device. The image forming device comprises an information obtaining unit to obtain at least one of target data and information specifying the target data from one of internal and external memories; a transmission unit to transmit the obtained information to the information processing device; and a image formation unit to execute an image formation process for data generated by converting the target data into data having a data format which the image forming device is able to handle. The information processing device comprises a conversion unit configured to convert the target data into the data having the data format based on the obtained information; and a second transmission unit configured to transmit the converted data to the image forming device.