The purpose of this study is to find a way of solving on parking problems at apartment complex through the trend analysis research of the parking demands according to the housing unit size. The subjects of this study are high-rise apartment complexes in Daegu city which are constructed within 10 years. The parking demand according to the housing unit size at apartment complexes had been surveyed every July for 4 years from 2000 to 2003. Specially, we knew that the parking demand of $85 m^2$ below sized housing unit at apartment complex was exceeded architectural regulation of parking supply, and the parking demand of $85 m^2$ over sized housing unit at apartment complex was kept within architectural regulation of parking supply. And, the estimating formula that can predict the future parking demand by the trend analysis according to the housing unit size at apartment complexes in Daegu city was gotten through this study. But, in order to get more accurate estimating formula, it should be based on data of funker research and investigation about apartment complexes and it should be studied continuously.