This paper investigates the relationship between the direction of a robot's face and its gaze as noticed by a person. Non-verbal information such as gaze movement or gestures is crucial to conversation between people. In particular, the effect of a gaze is most important in non-verbal communication because gaze movements convey various information such as timing of taking turns or a target indicated by a person. This paper argues that the important role of a gaze also applies to interaction between a human and a robot. In spite of the importance of the gaze, there has been no study on the relationship between a robot's head orientation and its gaze. We have conducted an experiment to investigate this relationship in an experimental environment named RM-RT, where the robot's head orientation is fixed to a particular person during a conversation. The results indicate that people notice the robot's gaze according to the robot's head orientation.