Differential invariants of prehomogeneous vector spaces studies in detail two differential invariants of a discriminant divisor of a prehomogeneous vector space. The Bernstein-Sato polynomial and the spectrum, which encode the monodromy and Hodge theoretic informations of an associated Gauss-Manin system. The theoretical results are applied to discriminants in the representation spaces of the Dynkin quivers An, Dn, E6, E7 and three non classical series of quiver representations.