PURPOSE: To display a complicated and various data in picture without extending memory by displaying this if the waiting error does not occur until the additional information comes after the transferring picture data are stored to the memory for saving the transferred sentence.

CONSTITUTION: When the capacity of a memory 3 for saving the picture is sufficient, the picture data, which is displayed presently, are saved to the memory 3, and thereafter, the picture data to receive the transferring from a host computer 1 are displayed through a memory 4 for saving the transferred sentence to a displaying device 5. When the error is detected, the data of the memory 3 saved earlier are read and displayed. On the other hand, when the capacity of the memory 3 is short, so that it cannot be saved, the picture data to receive the transferring from the computer 1 are stored to the memory 4 once, and thereafter, waiting is executed until the additional information to detect the error comes, and when it is detected and the error does not occur, the picture data are displayed at the device 5. Consequently, even when the data are not accommodated to the memory 3, the stable picture displaying can be executed.