Calibration with high accuracy can be realized even when performing the calibration while running on the actual road. Specifically, the calibration apparatus is mounted in a vehicle and includes: an image acquisition unit configured to acquire captured images obtained by a camera, which is mounted in the vehicle, capturing images of surroundings of the vehicle; a feature point extraction unit configured to extract a plurality of feature points from the captured images; a tracking unit configured to track the same feature point from a plurality of the captured images captured at different times with respect to each of the plurality of feature points, which are extracted by the feature point extraction unit, and record the tracked feature point as a feature point trajectory; a lane recognition unit configured to recognize an own vehicle's lane which is a driving lane on which the vehicle is running, from the captured images; a sorting unit configured to sort out the feature point trajectory, which is in the same plane as a plane included in the own vehicle's lane recognized by the lane recognition unit, among feature point trajectories tracked and recorded by the tracking unit; and an external parameter estimation unit configured to estimate external parameters for the camera by using the feature point trajectory sorted out by the sorting unit.