A data communication method is used to exchange data among a plurality of computers which are mutually coupled via a network. Each of the computers has a program which causes the computer to have a communicating function to transmit and receive data to and from one or more other computers, a data processing function to process data which are transmitted and received, and an output function to output data to an output section depending on a process of the data processing function. The data communication method includes a storing step to store data received by the communicating function by the data processing function in one computer when receiving data from one or more other computers by the communicating function, and a mode judging step to judge whether or not to output the received data to the output function of the one computer depending on a mode attribute of the received data and a communication mode of the one computer.