  Let G be a simple algebraic group over C with the Weyl group W. For a
unipotent element u of G, let B_u be the variety of Borel subgroups of G
containing u. Let L be a Levi subgroup of a parabolic subgroup of G with the
Weyl subgroup W_L. Assume that u is in L and let B_u^L be the corresponding
variety for L. The induction theorem of Springer representations describes the
W-module structure of H*(B_u) in terms of the W_L-module structure of
H*(B_u^L). In this paper, we prove a certain refinement of the induction
theorem by considering the action of a cyclic group of order e on H^*(B_u). As
a corollary, we obtain a description of the values of Green functions at e-th
root of unity.
