A lens system includes a first lens which is formed of a medium exhibiting negative refraction, and a second lens having a positive refractive index. Accordingly, it is possible to provide a lens system in which a negative refractive index medium for which a curvature of field is reduced. Moreover, it is also possible to have a lens system in which a lens having a positive focal length and a lens having a positive focal length, which is made of a positive refractive index medium, are combined.