The formability of steel sheets in the press forming of large-sized autobody panels is strongly governed not only by the fracture but also by such surface deformation defects as minute unevenness, body wrinkle, and insufficient shape fixation. The strain analysis over the entire surface of autobody outer panels for more than ten years has suggested the importance of the fitting behavior of a sheet on the punch surface during the punch stroke, which is governed by the geometry of the panel and the die face, press operating conditions, and sheet mechanical properties, for the successful removal of surface deformation defects. The fittability of steel sheets is analyzed by using a fitting behavior diagram in which the height of a wavy wrinkle is plotted against the distance of the punch travel for various panel profiles, and is described in relation to sheet mechanical properties such as the yield point and the strain-hardening coefficient in the range of a small strain.