Regulation of NOx emissions from marine diesel engines (DE) by the International Maritime Organization (IMO) has been carried out globally since May 2005. In the near future, particulate matter (PM) will be regulated as well. In Tokyo, Japan, the control of emissions from coastal vessels in the harbor is being pushed forward. In addition, demand for diesel particulate filters (DPF) from shipping and ship management companies operating pure car carriers (PCC) and container ships is anticipated. The use of DPF prevents the pollution of cargo by the exhaust from DE generators while the ships are moored in harbor. Since 2007, Mitsui Engineering & Shipbuilding Co., Ltd. and Daihatsu Diesel Mfg. Co., Ltd. have been developing a DPF applying non-thermal plasma technology for an onboard 1MW generator using fuel oil with 2,000 ppm sulfur to address customers' needs. As a result, 50% and 70% soot reduction have been achieved for single and serial connection of DPF respectively under steady state conditions in bench tests of a pilot model. A performance test of the DPF for a 1MW scale DE has also been carried out. The details of the test work, the system automation, and the modifications for onboard deployment are described in this paper.