A wedge product of Schur rings was introduced by K.H. Leung and S.H. Man in order to classify Schur rings over a cyclic group. The wedge product presented by Leung and Man was defined in an internal form. The external version of wedge product of Schur rings was described by Evdokimov and Ponomarenko under the name “generalized wreath product”. The goal of this paper is to generalize this operation to arbitrary association schemes.