A data transfer method for a network system wherein a plurality of computers are connected to each other through a switched network is improved in terms of the TLB hit ratio. Each of the computers includes a main storage device, a processor for issuing a communication process command and a communication device for processing the communication command from the processor and communicating with another one of the computers through a switched network. The communication device includes a transmission section and a reception section each of which includes a TLB for retaining a plurality of TLB entries. When a communication command including information of that one of the computers which is a sending source is issued from the processor, the reception section determines that one of the TLB entries which is to be used in accordance with the computer of the sending source.