Hot Mix Asphalt mixtures are often used as the top layer of pavement structures to build roads worldwide. Hot Mix Asphalt (HMA) mixtures combine bitumen and aggregate to produce roads. This paper aims to determine the optimum bitumen content (OBC) and investigate combining glass fiber in HMA with replacing a partial glass fiber of fine aggregate by Marshall Stability. The Hot Mix Asphalt was produced by mixing aggregate with 4% to 6% bitumen to obtain OBC to use in Hot Mix Asphalt Modified with glass fiber. Meanwhile, HMA modification was produced by mixing aggregate and OBC bitumen with 1% to 6% replacement glass fiber as a partial fine aggregate to improve the properties of Hot Mix Asphalt (HMA). Marshall Stability test, Aggregate Impact Value (AIV), Aggregate Crushing Value (ACV), Penetration Point, and Softening Point test was conducted. The effects of glass fiber in terms of stability, flow, stiffness, void in the total mix and void-filled bitumen in Marshall stability are investigated and compared with the control sample. The Optimum Bitumen Content (OBC) using Marshall Stability was chosen at 4.7% as OBC due highest stability value and passed in requirement standard JKR 2008. After analysis, the stability obtained for HMA Modified showed that adding 1%, 2%, and 3% glass fibers contributed to the highest stability values and passed the standards of parameters required by JKR 2008. Therefore, this paper can be concluded that the presence of glass fibers can significantly improve the performance of Hot Mix Asphalt (HMA).