It is well known that spatial equilibrium model is used as an efficient analytical tool of international trade. But it is very difficult to take specific duties and ad valorem duties into consideration when we try to apply the spatial equilibrium model to analyze the real international trade under complex tariff quota system. This paper is the sequel of Shono and Kawaguchi (1999), which present a spatial equilibrium model of perfectly competitive international trade under real tariff quota system with specific duties and ad valorem duties, but which does not present such a model of imperfectly competitive international trade. In this paper, based on the concept of shadow prices and Linear Complementarity Problem, we show how to take specific duties and ad valorem duties into consideration when we try to apply the model, and present a spatial equilibrium model of international trade, which can be used as an efficient and general analytical tool of oligopolistic international trade of some type under real traiff quota system with specific duties and ad valorem duties. We also present simple examples of the model and solve the example problems to get equilibrium solutions. Implications of this paper and problems to be solved in the future to present similar models of imperfectly competitive international trade of different type are summarized in the last section of this paper.