This paper presents the disributions and variations of CO, $CO_2$, number of people and temperature in underground shopping center and subway of Seomyeon and Jagalchi in Pusan, Korea for two times during October and November in 1993, respectively. NDIR analyzer is used for the analysis of CO and $CO_2$. The temperature is obtained from a mercury therometer. The results o( observation and analysis show that the variation of $CO_2$ is strongly related to number of people and temperature. The correlation coefficients between temperature, COB and Number of people are higher than 0. at both of places. The pollution of CO2 of Seomyeon is higher than that of Jagachi in underground shopping center. However, CO is not correlated with the temperature and the Number of people. From the results, we found that the indoor air quality monitoring system is needed for the prevention of the underground air Pollution. Key Words : CO, $CO_2$. Correlation coefficient, Air quality monitoring system, Underground aye Pollution