The objective of the research was to conduct economic analyses on the mobile satellite internet service in high speed moving object. From April of 2008, Korean Train Express over the speed of 300Km/hour has provided the paid wireless internet service to their passengers; however, the current service has shown limitations such as frequent disconnection, delay, or video play back freeze in tunnels. A survey was conducted to investigate the characteristics of korea express passengers in their service usage. Based on the survey, a system that integrates the satellite service into the existing wireless internet service was suggested, and its economic analyses were performed to confirm the economic feasibility on the development of the system. The economic analyses were performed with internet usage rate scenarios(8%, 6%, 2%) and fee scenarios (1,000 won, 1,500won, 2,000 won). Among the three scenarios, 6% with 1,500won gains economic justification as 8.3 billion Won of net present value and 15.5% of internal rate of return.