An image pickup device for detecting a moving speed of a shot object and a method thereof are described. First, a coordinate of the image pickup device and a coordinate of the shot object are obtained at a first time point. Next, a coordinate of the image pickup device and a coordinate of the shot object are obtained at a second time point. Then, a moving distance of the shot object is calculated according to the coordinates of the shot object at the first and second time points. A moving speed of the shot object is calculated according to a time difference and the moving distance. Afterward, the obtained moving speed is displayed on the image pickup device, such that the user knows about the moving speed of the shot object.