Halal as a quality of a food should be maintained from seed to fork. Each actor in a supply chain should not violate halal standard for the supply chain to produce halal food. For a firm to produce halal foods, not only should the firm process the foods according to Islamic rule, it also should confirm that it use only halal ingredients. However, halal is credence quality attributes that cannot be seen easily. Therefore, halal food producer should maintain relationship with its supplier well. The objective of this paper is to simulate behavior of halal food producer in terms of choosing and build relationship with its supplier. The research is performed using agent based modeling, and employed study case of halal food producer in Tokyo.