The Dungcas Beach Defense Guns are an old World War II Japanese fortification in the United States territory of Guam.

This fortification was built by the 48th Independent Mixed Brigade of the 29th Division of the Imperial Japanese Army, during its occupation of the island 1941–44.

The guns from this position were probably fired on landing Allied forces during the 1944 Battle of Guam, in which the United States retook the island.

The guns were removed from their original locations in 1992 to be treated for corrosion and to enable the development of the Onward Beach Resort.

Both guns are on display at the pool area of the Onward Beach Resort as of June 15, 2020.