The magnetization curves of melt-spun ribbons of Nd-Fe-B with (BH)max = 16 MGOe have been measured in pulsed high magnetic fields up to 400 kOe to examine the applicability of the law of approach to ferromagnetic saturation to highly anisotropic uniaxial ferromagnets. The magnetization in the region M≥0.95 Ms can be described well with the law of approach to saturation. From the analysis of the magnetization curve, the spontaneous magnetization, effective anisotropy constant and high-field susceptibility are estimated at room temperature. These values are consistent with those evaluated from single-crystalline data of Nd2Fe14B.