Provided is a travel route estimation device capable of accurately estimating, without excessively increasing communication load of the device, a shape of a travel route even when one's own-vehicle is traveling on a travel route that does not have any objects installed on the route. A calculation section calculates and successively stores a radius of curvature of the travel route based on a yaw rate detected by a yaw rate detection section and on a traveling velocity detected by a velocity detection section. When conducting a filtering process for reducing variation of the calculate radius of curvature, the calculation section selects a filtering constant for multiplying the stored radius of curvature in accordance with the type of the travel route of the own-vehicle, and generates information representing a radius of curvature obtained by conducting at least one filtering process by using the selected filtering constant.