There is provided a network system, comprising: a communication device communicating with an external device via a first network, an output device, and a first storage device stored with first data. The communication device, the output device and the first storage device communicate with each other via a second network. The communication device includes a first communication unit to communicate with the external device, a conversion unit which converts the first data into second data to be processed by the output device, a second communication unit which communicates with the output device, a second storage unit stored with information indicating correspondence between the first data and the second data, a first control unit to transmit the first data to the external device according to a transmission instruction, and a second control unit to transmit the second data. The output device includes a third communication unit which communicates with the communication device, a selection unit to select data to be outputted, an output unit which outputs the selected data, an instruction unit which issues the transmission instruction, and a third control unit to transmit the transmission instruction to the communication device.