Using the Korea Labor Income Panel Study 1998~2007, this research shows that job training has a significantly positive impact on income growth over this period. To access the concern that the effect of job training could be differentiated by educational level and wage quantile groups, we estimated the impact of job training by diverse human capital and structural variables. The results demonstrate that there are significant wage effect by educational levels and vocational training between wage quantile groups. Workers who is involved in lower quantile group are likely to have lower rates of income return of job training, but their rate of return is increasing by recent years. The relatively more advantaged workers such as highly educated, male, employed in big companies and high-income group have substantially increased their chances of job training in recent years than do relatively disadvantaged workers. The growth of income inequality is caused by the fact that the effect of education with high-income group is higher than the effect of job training with low-income group.