A size spectrum of black magnetic spherules which were collected from deep-sea sediments was obtained. Siderophile element (Fe, Co, Ir, and Au) concentrations in 100 spherules, each of them larger than 100 μm, were determined with instrumental neutron activation analysis. About 20% of the spherules showed (Ir/Fe) and (Co/Fe) ratios which cannot be explained clearly by an iron meteorite parent for the spherules. Further, there was no strong correlation between the size and the chemical concentration rations (Ir/Fe), (Co/Fe), and (Au/Fe)) of the spherules.