1. A controlling method for inputting messages to a computer, by which a practical mouse is needless, and the control function of mouse being formed by a capturing image of a video camera, the method including the following steps: (A) capturing an image of a referring background and an object image different with that of the referring background by a video camera; (B) capturing a maximum point in Y axis as the A point of a cursor; (C) capturing a maximum point in X axis as the B point of a click; (D) monitoring movement of pointer A, and (E) monitoring a distance between the pointers A and B, and as it is varied to be larger than a set value .sub..DELTA. AB, generating a click selecting function.