It is a major challenge in HRI to design a social robot that is able to direct a target human's attention towards an intended direction. For this purpose, the robot may first turn its gaze to him/her in order to establish eye contact. However, such a turning action of the robot may not in itself be sufficient to make eye contact with the target person in all situations, especially when the robot and the person are not facing each other or the human is intensely engaged in a task. In this paper, we propose a conceptual model of attention control with five phases: attention attraction, eye contact, attention avoidance, gaze back, and attention shift. We conducted two experiments to validate our model in human-robot interaction scenarios.