The development of transportation infrastructure impacts migration, production, and other economic activities along with it. In this study, we conducted a multiregional computable general equilibrium simulation analysis to assess the effects that the proposed 2027 high-speed railway, the Linear Chuo Shinkansen in Japan, will have on population migration. The 47 prefectures ordained by the Japanese administrative unit were considered, and the simulation potential workforce population was taken as 110 million. The population is concentrated in the Tokyo metropolitan area. As per our simulation, once the proposed high-speed railway opens, “travel costs” (comprising time and the monetary costs of traveling) will decrease. This situation will stimulate economic activities and lead people to migrate to the prefectures where the economic environment improves. The results show that this development will ease extreme population concentration while simultaneously increasing employment and production values. However, additional analysis indicates that further development of the Linear Shinkansen to strengthen the current high-speed rail on the route to Tokaido will increase population concentration.