A predicted course estimating apparatus for estimating a predicted course of the own vehicle, includes: a data acquiring means for acquiring turning data that indicates a turning direction of the own vehicle; a filtering means for removing a high-frequency component that is included in the turning data; a course predicting means for calculating an estimated value for course prediction of the own vehicle, based on the turning data that has been filtered and a speed of the own vehicle; a determining means for determining whether the own vehicle is traveling a part of a road where the shape changes; and a characteristics changing means for changing the extent of removing of the high-frequency component by the filtering means when it is determined that the own vehicle is traveling a part of the road where the shape changes.