This paper proposes a behavior model for swarm robotic systems that can be externally guided, with agreement on their heading direction with other robots. Alignment rules are often used in conventional studies, and have been shown to be effective for generating flocking behavior for robotic swarms. However, this rule is hard to implement to real robots due to technical difficulties. In order to tackle this challenge, we implement two types mechanisms. The first mechanism is two biomimetic rules: (1) a frontal-sector interaction rule in surf scorters, and (2) a leader rule for providing information about the desired direction to its flockmates. The second mechanism is estimation of the moving direction of other individual by using visual information. By conducting physical experiments, the effectiveness of the proposed method is evaluated quantitatively.