PURPOSE: To realize a lens which has a variable power ratio of twice or more, also is compact, and has high performance in all magnifications by constituting a lens system of a front group and a rear group, and also satisfying a specified condition.

CONSTITUTION: A variable power read lens system is constituted of a front group having a negative focal distance, and a rear group having a positive focal distance, from an object side, and in case when a variable power is executed to a magnification from a low magnification, it is executed by reducing an interval of the front and the rear groups, enlarging a focal distance, and also reducing a distance between an object and an image. Also, an expression I and an expression II are satisfied, when fmin, fmax, K, and f1 denote a focal distance of the whole system of a low magnification side, a focal distance of the whole system of a high magnification side, a variable power ratio of a use magnification, and a focal distance of the front group, respectively. In this way, a variable power read lens system which has a large variable power of two times or more, also is compact, and has a high performance in all magnifications can be obtained.