A method and an apparatus for evaluating ablation conditions easily and for ablating a target object accurately. The method includes irradiating a reference object with a laser beam under laser irradiation conditions determined to form a second curved surface shape on the reference object having a first curved surface shape approximate to a curved surface shape of the target object, measuring a third curved shape which has actually been formed by the laser irradiation, and determining a discrepancy between the second and the third curved surface shapes. Then, data about ablation or data for controlling a laser irradiation apparatus are corrected based on results of the determination.