A method, an apparatus, and a program of predicting an obstacle course, capable of appropriately predicting a course of an obstacle even under a complicated traffic environment, are provided. For this purpose, the course, which the obstacle may take, is predicted based on the position and the internal state of the obstacle, and at the time of the prediction, a plurality of courses are probabilistically predicted for at least one obstacle. When there are a plurality of obstacles, the course in which different obstacles interfere with each other is obtained from the predicted courses, which a plurality of obstacles may take, and the predictive probability of the course for which the probabilistic prediction is performed from the courses in which they interfere with each other is lowered. Probability of realizing each of a plurality of courses including the course of which predicted probability is lowered is calculated.