A device for measuring the quantity of material flown in seawater is provided to accurately measure the quantity of material flown in the seawater from surface sediment by circulating the seawater flown in a parallel direction for uniformly contacting the whole surface of the collected sediment with the seawater. The device comprises: a housing which includes a supply portion(12) through which seawater is supplied, a receiving portion(14) to receive collected sample, discharge portions(16), each of which is formed in sequence by each partition installed at bottom with predetermined height and ...