When we wear contact lenses for correcting astigmatism, we often experience the axis-rotation of contact lenses that is happened in case we could not fit the axis of lens exactly or by the eyelid used to blink. In this case, because the exact correcting state becomes in the wrongly correcting state, the asthenopia is led, and the decline of eyesight can be led. For this reason, we need to know axis-rotating degrees of contact lenses. If a contact lens rotated, a residual astigmatism may be detected in the refraction examination after wearing. Using this, we developed a program that calculates the axis-rotating amount of contact lenses.