Abstract: The present invention provides a lens system for projecting to a screen a video image formed on a face plate of a cathode ray tube. The lens system comprises, from the screen side to the tube side: a first positive lens unit; a second positive lens unit; a third negative lens unit having a screen side surface convex to the screen side; a fourth lens unit of bi-convex lens; and a fifth negative lens unit having a screen side surface concave to the screen side, at least the fourth lens unit being made of glass material, wherein the lens system includes at least one aspheric surface and fulfills the following conditions: ##EQU1## wherein; f represents the focal length of the whole lens system; f.sub.1 represents the focal length of the first positive lens unit; f.sub.2 represents the focal length of the second positive lens unit; f.sub.3 represents the focal length of the third negative lens unit; and .nu..sub.3 represents the Abbe number of the third negative lens unit.