In [23], we studied some properties of standard L-functions attached to sym'( Iθ-valued Siegel modular forms of weight det* (x) sym*. More precisely, let det* (x) sym be an irreducible rational representation of GL(n, C) with representation space sym (F), where V is isomorphic to C and sym'(F) is the /-th symmetric tensor product of V. Let / be a sym'( F)-valued holomorphic cusp form of weight det* ® sym for Sp(ny Z) (size 2n). Suppose / is an eigenform, i.e., a non-zero common eigenfunction of the Hecke algebra. Then we define the standard L-function attached to / by