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Untung Jawa Island, a tourism island north of Indonesia Capital, Jakarta has been experiencing severe erosion in the coastline. Therefore, the beach nourishment and breakwaters were constructed. This paper aims to evaluate the effectiveness of breakwater in protecting beach nourishment project in Untung Jawa island, Indonesia with using process-based numerical modelling of sediment transport and morphological change Delft3D. There are four existing breakwaters at the offshore side, and there are two at the nourishment project. The numerical simulation including flow-wave coupling with the duration of 45 days and the use of morphological acceleration of 24 giving the result of 3 years of total sediment transport. In the flow model, tidal data is used at the seaward boundary and neumann water level at the lateral boundary, sediment diameter D50 0.2 mm. In the wave model, different wave scenarios are used including wave height, wave period and wave direction. In addition, the different scenario of breakwater height also discussed in this paper, and finally, the volume of sand deposits and wash out are also calculated.