An optical instrument of the present invention comprises a first ZM group drive section for moving a first lens group, a second ZM group drive section for moving a second lens group, a storage section for storing positional information on position of the first and second lens groups corresponding to focal length, and storing information relating to the movement speed of the first and second lens groups, and a control section for controlling position of the first and second lens groups based on positional information of the first and second lens groups, and controlling the first and second drive sections so as to move the first and second lens groups by synchronizing the movement speed of the first and second lens groups based on information relating to movement speed of the first and second lens groups.