A viewer method and a viewer device are capable of more rapidly reproducing desired screen data. A jump processing unit instructs a reproduction unit to jump to and reproduce arbitrary screen data based on difference data between sequentially retrieved screen data. The screen data a user desires to check is often screen data of when the difference data is large, that is, screen data of when the amount of change in the retrieved screen data is large such as when an error has occurred. Thus, the desired screen data can be more rapidly reproduced by jumping to and reproducing the screen data based on the difference data.