1. An ablation apparatus for ablating a surface of a cornea to form a transition zone for myopia correction by laser beam, comprising: a laser source for emitting a laser beam; an ablation optical system for ablating the surface of the cornea by the laser beam emitted from said laser source; ablation area changing means for changing an ablation area on the cornea; cornea shape forming means for forming a shape of an optical zone of the cornea, the radius of curvature of the shape of the optical zone being larger than the radius of curvature of a pre-operation cornea, by superposing the laser beam through said ablation optical system; input means for inputting data related to the transition zone, the transition zone to have a shape for smoothly connecting said optical zone with a non-ablation area; and control means for determining the shape of said transition zone, based on the data and based on a curvature of a pre-operation cornea and a desired post operation cornea, and for controlling movement of said ablation area changing means to achieve the shape of the transition zone.