An image capturing lens system includes four lens groups which include eight lens elements. The four lens groups are, in order from an object side to an image side: first, second, third and fourth lens groups. The eight lens elements are, in order from the object side to the image side: first, second, third, fourth, fifth, sixth, seventh and eighth lens elements. The first and second lens elements respectively have positive and negative refractive power. At least one lens element in the second through fourth lens groups has an inflection point. A focal length of the image capturing lens system is varied by changing axial distances between the four lens groups in a zooming process. The second lens group is moved relative to the first lens group along an optical axis in the zooming process. The image capturing lens system has a long-focal-length end and a short-focal-length end.