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 of observation and analysis show that the variation of CO_2 is strongly related to number of people and temperature. The correlation coefficients between temperature, CO_2 and number of people are higher than 0.85 at both of places. The pollution of CO_2 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.