Based on the results of the previous two reports, we attempted to inhibit the accumulation and proliferation of marine fouling organisms on vinyl plates through the application of a weak electric current via titanium wire electrodes. Plates were set in two sea areas near the National Fisheries University ; one area was subjected to an electric current, and the other area was used as a control. The experiment was carried out over two periods ; June to August 1999 (3 months : 1st period), and October to January 2000 (3 months : 2nd period). using solar cell modules and rechargeable NiCad batteries, we supplied a constant current of about 70 mA at 5 V during the .first period the same as in 1998. We used only solar cell modules during the second period. The application of 70 mA at 5 V was found to be effective in preventing the adhesion of bamacles through a year. It was estimated that the time of the voltage larger than 8V, which is expected to be effective to prevent fouling by seaweeds from the result in 1997, had been applied during the second period was about 5.3 hours a day. Hence it was clarified that such electrical conditions were not effective to prevent fouling by marine organisms. We should confim the prevention of fouling under the condition where a voltage larger than 8 V is always applied and also clarify the affected area by the electrical conditions.