Abstract: A placer gold separating method includes subjecting placer gold-and gold ore-containing sand and gravel layers accumulated on the bottom of the water of a river and placer gold- and gold ore-containing sand and gravel layers formed deep in the ground to excavation or suction excavation by utilizing a water pressure difference. This causes a mixture of the excavated or suction excavation placer gold- and gold ore-containing sand, gravel and water to flow horizontally by the action of a pressure fluid. The placer gold and gold ores are separated by utilizing a specific gravity difference while the mixture is flowing. A placer gold mining boat used to practice this method is provided thereon with a combination of a suction excavation component, a mixture transfer component, a component for separating placer gold by utilizing a specific gravity difference, and a component for discarding the remaining mixture from which the placer gold has been separated.