We developed a novel at-wavelength metrology for the surface figure of hard x-ray focusing mirrors. The metrology, which evaluates the wave-front error of the focusing beam, is based on the numerical calculation of intensity distribution profiles around the focal point. We demonstrated the atwavelength metrology of a total reflection mirror. The recovered phase error profile of the test mirror using the atwavelength metrology was in good agreement with the profile measured using an optical interferometer. This result indicates the effectiveness of the developed metrology. This technique is expected to be applied to manufacturing processes for realizing diffraction-limited nano focusing optics.