A high magnification zoom lens system includes first through fifth lens groups respectfully arranged sequentially from an object side. At least one of the first through fifth lens groups moves during magnification change, the first lens group comprises a reflection member, and the zoom lens system satisfies the conditions 3.8<=fT/gW<=6.0 and 1.50<=LT/fT<=1.88 wherein ''fW'' denotes the focal distance at the wide angle position, ''fT'' denotes the focal distance at the telephoto position, and ''LT'' denotes the overall length of the zoom lens system from the lens surface on the object side to an image plane, at the telephoto position.