An environmentally sound management of plastic waste in Semarang City is necessary due to increasing plastic waste generation; limited capacity of Jatibarang Final Disposal; dangers of open burning of plastic waste; pollution of water resources both surface water and sea water; and limited amount of raw materials for the manufacture of plastic resin. This study aims to present the assessment of plastic waste management from collection to final disposal as well as its estimated generation. A field study was conducted to identify the material flow of plastic waste, particularly PET bottles. To estimate the potential generation of plastic waste, a top-down approach was used. The volume of plastic waste in Semarang reached 16.28% of the total municipal waste, in which the highest part of inorganic waste. The total estimated plastic waste generation in Semarang City, particularly from households, was 1012.486 m3/day. There is an urgent need for improving the plastic management in Semarang due to existing low recycling rate.