This paper describes the design idle motions which service robots act in its standby state. In case of the robots developed so far, they show proper reactions only when there is a certain input from human or environment. They cannot perform in a standby state which means there is no input. If a robot does not make any motion in its standby state, users may feel that the robot is being turned-off or even out of work. On the other side, if the robots can make idle motions such like human at the standby state, then they are expected to make people feels that they are alive and is more likely to interact with them. In order to find the behavioral patterns at the standby state, we observed clerks at the information center via video ethnography, and idle motions are extracted from video data. We analyzed idle motions, and apply extracted characteristics to our robot. Moreover, by using the robot which can show those series of expression and action, our research needs to find that people can feel like they are alive.