The magnetization process of the spin-S Heisenberg antiferromagnet on the kagome lattice is studied by the numerical-diagonalization method. Our numerical-diagonalization data for small finite-size clusters with S = 1, 3/2, 2, and 5/2 suggest that a magnetization plateau appears at one-third of the height of the saturation in the magnetization process irrespective of S. We discuss the S dependences of the edge fields and the width of the plateau in comparison with recent results obtained by real-space perturbation theory.Frustrated spin systems have attracted much attention from many condensed-matter physicists. One of the fascinating systems among them is the kagome-lattice Heisenberg antiferromagnet. Unfortunately, our understanding of this system is still far from complete in spite of many experimental and theoretical studies. In the S = 1/2 system, in particular, discoveries of several realistic materials such as herbertsmithite, 1, 2 volborthite, 3, 4 and vesignieite 5, 6 have accelerated theoretical studies. 7-29 However, there remain some unresolved issues; one of them is the spin-gap problem of whether the spin excitation above the singlet ground state is gapped or gapless.On the other hand, fewer studies on S > 1/2 cases have been carried out. As candidate S = 1 kagome-lattice systems, m-MPYNM·BF 4 , 30, 31, 33 and KV 3 Ge 2 O 9 34 are known. Theoretical studies 9, 35-39 for the S = 1 case are also limited. Studies on the S > 1 cases have only started recently; candidate kagome-lattice systems of Cs 2 Mn 3 LiF 12 40 for S = 2 and NaBa 2 Mn 3 F 11 41 for S = 5/2 have been reported, together with theoretical studies 42-44 as well as an analysis based on the semiclassical limit. 13 Under these circumstances, then, we are faced with a question: do any systematic behaviors exist in the spin-S kagome-lattice Heisenberg antiferromagnet under magnetic fields? The purpose of this letter is to extract such systematic behavior of the magnetization processes of this model for various S by numerical-diagonalization calculations that are unbiased against approximations. With the same motivation, Zhitomirsky recently investigated the frustrated Heisenberg model under magnetic fields by real-space perturbation theory taking into account fluctuations around a classical configuration. 44 He found that in the magnetization process of the kagome-lattice antiferromagnet, the so-called uud state is stable at one-third of the height of the saturation, at which a magnetization plateau appears irrespective of the value of S. He also derived an expression for the 1/S expansion for both the edge fields of this height. The comparison between the * E-mail: hnakano@sci.u-hyogo.ac.jp † present numerical-diagonalization results and the results from real-space perturbation theory should contribute to our understanding of the frustration effect in the kagome-lattice antiferromagnet.The Hamiltonian that we study in this research is given by H = H 0 + H Zeeman , whereandHere, S i denotes the spin operator at site i, where the sites are th...