We answered to the research questions as follows. Has there been any change in the moderating effects of research and development (RD) between open innovation (OI) and firms' performance of small and medium enterprises (SMEs) in the South Korean manufacturing sector since the global financial crisis in 2007. And, if so, how about the changes? First, with the increase in OI of SMEs in the South Korean manufacturing sector, their performance moved in an inverted U-shaped curve in 2005, and 2014 altogether. Second, the RD investment by SMEs in the South Korean manufacturing sector had a net effect on their performance in 2005, and 2014 altogether. Third, the RD investment by SMEs in the South Korean manufacturing had accelerated the effect of OI on their performance in 2005. But, the RD investment by SMEs in the South Korean manufacturing sector failed to moderate the effect of OI on their performance in 2014.