The waste materials generated from construction activities have an impact on the increasing costs incurred by contractors. As construction costs increase for each project, it poses a potential loss for the project, especially considering the significant amount of wasted materials. The aim of this research is to analyze the model of the influence of causes of leftover materials on construction cost losses in high-rise buildings in Jakarta. This study was conducted based on data collected from 12 distinct projects, with a total of 21 respondents. The sampling technique employed in this study utilized questionnaires. The design planning, material procurement, material handling, work implementation, and residual materials variables were found to have an impact on construction cost losses. Among these variables, material procurement and design planning were identified as the most influential factors contributing to construction cost losses. Construction cost losses were derived from indicators with the highest averages, specifically in the variable of leftover material procurement for indicator X2-1, with an average score of 5.19, and in the design planning variable for indicator X1-1, with an average score of 5.05. These indicators are related to "material orders" and "design changes," respectively.