This paper aims to present the basic data to establish resonable building maintenance standards by investigating and analyzing the actual conditions of maintenance for service facilities and the problems due to the situation. The subject buildings of investigation are 10 stories and above off ice buildings in Seoul. The results obtained from this study are as follows. 1. The equipment service life related to air-conditioning system is known as around 9years in case of breakdown maintenance and around 13 years in case of preventive maintenance. 2. The total mechanical room area against the total floor area is $4.40\%$, and the ratio of air-conditioning room area is $1.78\%$ on an average.