This study analyzed the composition of the time use and childcare time use of working mothers and fathers of Generations X and Y, differences between generations, differences between mothers and fathers, and factors affecting childcare time. We analyzed the lifetimes of working parents of preschool children(n=2,287) using Statistics Korea's Time Use Survey for 2014 and 2019. The main results are as follows: First, when comparing the lifetimes of Generations X and Y, in 2014, Generation Y mothers had longer commuted times, whereas for fathers, there was no difference between generations. Second, comparing the time use of Generations X and Y, regardless of the survey period, Generation Y mothers had longer sleep times than their counterparts, while Generation Y fathers had longer time in sleep, home management, and childcare than their counterparts. Third, in analyzing the factors affecting parents' childcare time for mothers of both generations, the less sleep times, mealtimes, working times, commuted times, home management times, and leisure times, the longer the childcare times. In the case of fathers, for Generations X and Y, the less sleep times, mealtimes, market work times, commuted times, and leisure times, the more childcare times. However, in Generation X fathers, home management time and the gender role attitude affect childcare time. While the generation gap was not clear for mothers, it was confirmed for fathers. Therefore, it was proposed not only gender differences but also generational characteristics should be taken into account to provide implications for child care policies, especially for fathers, in community care support systems incluing education and counseling programs.