Predicting the prices of agricultural products is very difficult because there are so many uncertain factors in the demand and production of the agricultural products. The Box-Jenkins methodology is one of strong tools to forecast especially for the short-term or medium-term using historical observations of time series. In this paper, the Box-Jenkins methodology is applied to find a model to forecast future broiler prices. It turned out that short-term forecast was quite accurate, while mid-term forecast was not accurate because of some economic factors such as decrease of beef demand.