On the offset printing the control of fountain solution is very important and difficult. By the progress of technology and electronics, we have been able to solve this problem nearly. As the waterless offset printing doesn't need to use water, this system will set us free from the trouble about it, and may lead us to automation of offset printing in the near future.This paper describes about the principle of waterless offset printing system and its merits or demerits compared with the conventional wet offset printing system.