Disclosed is a bifocal lens constructed such that the lens is not easily damaged when hit by flying fragments and, moreover, able to obtain a consistent focal length with a simple construction. The lens is equipped with a transparent substrate having transparency and rigidity, a transparent resilient body having transparency and elasticity, a transparent fluid enclosed in the space between the aforementioned transparent substrate and the aforementioned transparent resilient body, and a mechanism that induces changes in the shape of the aforementioned transparent resilient body. Changes are induced in the shape of the transparent resilient body to form the desired shape in the two states of the lens which comprises the transparent fluid enclosed in the space between the transparent substrate and the transparent resilient body, making it possible to obtain the desired characteristics (accurate optical characteristics) in either of the two states.