This paper tries to measure the spill-over effect of the production and investment of telecommunication service industry (hereafter telecommunication industry), using the most recent data of 2003 input-output tables. The results are summarized as follows. First, the industries which have the biggest spill-over effect from the production of telecommunication industry is miscellaneous business service (including the sale commission of telecommunication service), other engineering services (including royalty), and business consumption. Second, the production of telecommunication industry induces more value-added, and less production, less import, and less employment than related industries such as radio and television equipment, communications and broadcasting equipment, and computer and peripheral equipment. Third, while the investment of telecommunication service amounts to 15% of its production, the effect of the investment on production, value-added, consumption, and employment reaches 70% of that of its production. The policy implication of this paper is that the telecommunication industry contributes to overall economy mainly through its investment.