This paper presents the result of the experimental examination by "passing each other" and "positional prediction" in simulated interactive situation between people and mobile robot. We have developed four prototype robots based on four proposed methods for preliminarily announcing and indicating to people the speed and direction of upcoming movement of mobile robot moving on two-dimensional plane. We observed significant difference between when there was a preliminary-announcement and indication (PAI) function and when there was not even in each experiment. Therefore the effect of preliminary-announcement and indication of upcoming operation was declared. In addition the feature and effective usage of each type of preliminary-announcement and indication method were clarified. That is, the method of announcing state of operation just after the present is effective when a person has to judge to which direction he should get on immediately due to the feature that simple information can be quickly transmitted. The method of indicating operations from the present to some future time continuously is effective when a person wants to avoid contact or collision surely and correctly owing to the feature that complicated information can be accurately transmitted. We would like to verify the result in various conditions such as the case that traffic lines are obliquely crossed.