Focusing on internationalization and convergence among important environmental changes in the service industry, this study deals with whether these environmental changes has a significant impact on service firms' R&D investment through empirical analysis. To this end, an empirical analysis was conducted on service firms listed on the Korea Securities Market(KOSPI) from 2010 to 2022, and the main results are as follows. First, it is found that the higher the degree of internationalization measured by exports compared to total sales, the higher the R&D intensity. Korean service firms are in the early stages of overseas expansion because internationalization is relatively slow compared to manufacturing firms. As previous studies point out, in the early stages of internationalization, cost of foreignness such as local government regulations, competition with local firms, and demands for localization are likely to cause poor performance, and in response, service firms are trying to strengthen their internal capabilities by expanding R&D investment. Second, how much competitive pressure service firms face due to convergence is measured by the proportion of sales of one of the largest products(services) in the company, and the analysis finds that service firms under more competitive pressure due to convergence are more active in R&D investment. The analysis shows that service firms that generate sales through diversified products(services) are more exposed to competitive pressure due to convergence than sales centered on major products(services) that have solidified entry barriers, and R&D investment is increased to cope with this. Empirical results suggest that R&D investment, like manufacturing firms, can be used as an important means to strengthen their competitiveness, and it is expected that R&D investment research on various topics previously conducted on manufacturing companies can be expanded to service firms.