We report experimental results of magnetic susceptibility and the high-field magnetization of Yb_1-xY_xInCu₄ under various fixed temperatures, most of which are found to be explained by the calculation according to the modified Falicov-Kiwball model, although the observed sharp transition in substituted YbInCu4 is unexpected by this model. By proper scaling of the (Hv Tv) data extracted from the high-field magnetization measurements, we can collect all of the data from the system of Yb_1-xY_xInCu₄ onto a universal H-T phase diagram, but it is shifted from the relationship expected by Falicov-Kimball model.