PURPOSE: To provide a three-focus switching variable power lens system, etc., at low cost.

CONSTITUTION: The variable power lens system has a 1st afocal conversion lens system composed of a concave lens L1 which is made of plastic and has aspherical surfaces as both its surfaces and a concave lens L2 in order from the object side and a 2nd afocal conversion lens system composed of a concave lens L3, a cemented concave lens L4 of a convex lens and a concave lens, a plastic aspherical convex lens L5, and a cemented convex lens L6 of a concave lens and a convex lens, has a stop arranged, and also has an image forming lens system composed of a convex lens L7, a concave lens L8, and a plastic aspherical convex lens L9, thereby serving as a wide angle lens. The 1st conversion lens system is rotated by 90° to obtain intermediate focal length through the constitution of only the 2nd conversion lens system and image forming lens system for photography through a through hole formed in the lens barrel of the 1st conversion lens, and the 2nd conversion lens system is rotated by 180° to obtain a telephoto lens.