This paper examines changes in the skill structure, skill level, and skill gap in Korea over the period 1993~2004, using raw data of the Survey Report on Wage Structure. Individual worker's skill score is estimated in the way of deriving/separating prediction values solely due to skill factors through regression on wage equation. The ranking of skill scores among occupations is largely consistent with those of previous literature using different skill indices from this paper. The key findings are summarized as follows. First, the relative structure of skills across occupations shows little change over the period in terms of the skill ranking. Second, considerable upskilling occurs in most occupations over the period, as predicted in the upskilling thesis. Third, employment size and proportion of low-skill occupations as well as high-skill occupations increase, implying skill polarization is occurring.