The development of asphalt modified with natural rubber, specifically Standard Indonesian Rubber (SIR) 20, improves the overall performance of asphalt. However, the mixing process presents challenges that can result in higher mixing and compaction temperatures. To overcome this, our research utilizes SIR 20 in micro form. This study aims to assess the effects of incorporating Micro Rubber SIR 20 (MR SIR 20) into bitumen on the fundamental rheological properties of asphalt and to explore the morphological characteristics of MR SIR 20 modified asphalt. The research was conducted through laboratory tests, examining key rheological properties such as penetration, softening point, ductility, and viscosity. For morphological analysis, tests included Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray Spectroscopy (EDS), and Fourier Transform Infrared Spectroscopy (FTIR). The laboratory tests involved adding MR SIR 20 in concentrations of 7%, 9%, and 11% to Pen 60/70 asphalt. The findings indicated that as the MR SIR 20 content increased, penetration values decreased, softening points rose, ductility diminished, and mixing and compaction temperatures were reduced. The decrease in penetration is attributed to the higher MR SIR 20 content, which enhances the absorption of lighter asphalt fractions and improves homogeneity. The rise in softening point compared to standard Pen 60/70 asphalt signifies a successful modification, driven by increased asphaltene and resin content and a reduction in maltene content in the bitumen. Consequently, MR SIR 20 modified asphalt can speed up the mixing process and lower the required mixing and compaction temperatures. SEM analysis of MR SIR 20 revealed a rounded morphology, uniformly distributed across the surface. EDS analysis identified sulfur, potassium, calcium, and zinc as the dominant elements in MR SIR 20, which play a vital role in enhancing the properties of Pen 60/70 asphalt in the mixture. Additionally, FTIR analysis showed the presence of alkane functional groups in MR SIR 20.