This study conducts an empirical study on which factors affect intellectual skills requirements for manufacturing production jobs, utilizing Survey on Skills Requirements of Jobs administered by KRIVET. Improving upon the case study results of Koike(1994) and Koike(2002) and by pure reasoning, we draw the following hypotheses: Repetitive jobs will demand lower intellectual skills, and change in the types of products, involvement in problem-solving tasks, and use of computer will demand higher intellectual skills. Additionally we also explore how automation affects intellectual skills requirements. We estimate OLS whose dependent variables are basic cognitive skills (math, reading, writing) requirements and general thinking skills requirements. The results of this study are as follows. First, involvement in problem-solving tasks, and use of computer have statistically significant positive effects on math, reading, writing, and general thinking skills requirements. Second, repetitive job has statistically significant negative effects on math, writing, and general thinking skills requirements. Third, change in the types of products has, at least weakly, statistically significant positive effects on math and writing requirements. Fourth, automation has statistically significant negative effects on reading and general thinking skills requirements. Overall, most of our hypotheses are supported. Finally we summarize and discuss the empirical results and draw the practical implications.