1. An automatic tracking method, comprising a light spot detecting step of detecting a light spot from a target supported on a moving object, a step of taking a moving image of said target and said moving object, a step of tracking based on the detection of the light spot, a step of performing image tracking based on said moving image in parallel to said tracking, a step of comparing a position of the target obtained by said tracking with a position of the image obtained by said image tracking, and a step of tracking based on a result of said tracking in case where said target position and said image position are within a predetermined range.