In factory automation (FA) industry, it is essential for the working environment using industrial robots to be provided with measures that assure operator's safety and good usability of machines. We have studied the operator's safety and usability of portable robotic operation terminals, and have developed the standardized terminals for one-hand operation suitable to many types of applications. The findings and knowledge we obtained through the development materialized recently as the new two-hand portable robotic operation terminal which is designed ergonomically. In this paper, we report on the new operation terminal which provides excellent operational safety and usability, and also a study on the effectiveness of wireless terminals for improving the usability of entire system.