Purpose: This study analyzes the optimal operation scheme of childcare centers in Korea to maximize the quality of childcare service by determining the number of children and number of teachers. Methods: This study employs a mathematical programming methodology called ``nonlinear integer programming (NLIP)`` to solve the optimization problems and compare the quality of childcare service of optimal solutions with those of present operation scheme. Results: It is very successful in obtaining the optimal solutions for alternative capacities and they guarantee the substantial improvement in the quality of childcare service. Conclusion: Though more variables should be adapted for defining the quality of childcare service robustly. it is possible to conclude that childcare centers should modify their operation scheme to improve the quality of childcare service.