PURPOSE: To reduce the cost and size of a 3-group variable focal length lens by moving only one lens group and equalizing image plane positions at both ends in a variable focal length range.

CONSTITUTION: This lens consists of the 1st lens group having positive refracting power, 2nd lens group having negative refracting power and 3rd lens group having positive refracting power. The focal length thereof is varied and the image plane positions are equalized by fixing the 1st lens group and the 3rd lens group and moving only the 2nd lens group. The 1st lens group consists of the combined lens of a negative meniscus lens the convex face of which is directed to the object side and positive lens the strong convex face of which is directed to the object side, successively from the object side. The 2nd lens group consists of two pieces of negative lens and one piece of positive lens, successively from the object side. The 3rd lens group includes at least three pieces of positive lenses and at least one piece of a negative lens. Aberrations are thereby corrected with good balance and the variable focal length lens of the small size and low cost is obtd.