This article aims to measure the economic impacts of the San-En-Nanshin Expressway that will be constructed through a prefectural cross-border area across Aichi, Shizuoka and Nagano Prefectures in Japan.　First, we present a simplified spatial computable general equilibrium model of the San-En-Nanshin region.　Then we attempt to measure the economic impacts of the San-En-Nanshin Expressway by applying the so-called shortcut method. The economic benefit of the expressway was estimated to be 24.4 billion yen which passes the cost-benefit criterion. The interregional benefit incidence is also described in this article. Recommendations for increasing the benefits are mentioned in the concluding remarks. JEL Classification: R11, R13, R41