Microplastics are emerging contaminants that degrade from textile plastic products, petroleum, and cosmetic equipment with sizes less than 5 mm. There are more than 70,000 settlements located along the Ciliwung River in DKI Jakarta that use the river water as a source of clean water. The most common type of waste found in the Ciliwung River to date is plastic waste, which can cause flooding and other disasters. The Ciliwung River can currently be found with microplastic pollution which has an impact on exposure to living things in the river, such as in case studies in the Ciliwung River estuary area. The problem is the exposure to 75% of blue panchax fish (Aplocheilus sp.) as many as 1.97 particles per fish with sizes of 300 to 500 μm. This research will focus on analyzing the dynamics of microplastic quantity in water and sediment of the Ciliwung River along with the correlation between field parameters and population density around the banks of the Ciliwung River. When viewed from the seven points that represent the Ciliwung River downstream to upstream in DKI Jakarta Province, the number of microplastics is in the range of 320-741 particles/L. For the dominating form, it can be analyzed that the majority of microplastic forms are fragments (97%), followed by fibers (2.9%) and pellets (0.1%). While in the sediment, the number of microplastics in the Ciliwung River sediment is in the range of 6560-10630 particles/kg. The population density factor has the highest correlation to the number of microplastics with a value of r = 0.702. This is associated between population density and high microplastic emission loads.