The present invention relates to a data communication method and apparatus comprising a noise information memory for storing noise information to indicate a degree of noise on a current communication line and capable of performing communications in a plurality of communication modes. The method and apparatus further comprising a mode memory for storing the plurality of communication modes in response to the degree of noise, and a mode change control unit for reading current noise information from the noise information memory and selecting the communication mode corresponding to the current degree of noise from the mode memory, and changing the current communication mode into the selected communication mode. The present invention provides an apparatus and a method for highly reliable data communication with simplified construction.