This study examines changes taken place in time spent of Korean couples on household work and childcare during the period 1999~2014. Data from Time Use Survey administered by Statistics Korea was used for the analysis. The factors brought about changes in time spent on housework and childcare were analyzed by estimating the Oaxaca-blinder model and the unconditional quantile regression model. Over the period of 1999~2014 Korean men increased their time spent on housework and care work but the amounts of changes were very limited. Korean women decreased her time spent on housework and still spent considerable amounts of time for childcare. On the average Korean men and women increased their time spent on childcare and the increase was more prominent in the middle and upper quantiles than in the lower quantiles. For men the changes in time spent were more likely attributed to non-structural factors such as social norms and perceptions. It indicates that there have been changes in men's perceptual attitudes toward household work and childcare although the influence was very weak. The decrease in time spent on housework by women is attributable not only to non-structural factors but also to a considerable extent to structural factors such as employment status. However, the increase in the amount of time spent on childcare of Korean women was due much more to non-structural factors than to structural ones. The negative effect of the structural factors on the amount of time women spent on childcare has been more than offset by the positive effect of non-structural factors. It suggests that psychological and emotional motives are more likely to shape Korean mothers' childcare pattern than socioeconomic factors.