Trace tramp elements (Zn, As, Sn and Sb) and other trace elements in pure iron certified standard materials, JSS003-4, JSS168-7 and JSS172-7, prepared by the Iron and Steel Institute of Japan were determined by instrumental neutron activation analysis (INAA). Four aliquot samples of each certified standard material (ca. 100-450 mg) were irradiated for 6 h at a thermal neutron flux of 3.7 × 1012 n cm-2 s-1 in the Rikkyo University Research Reactor. The irradiated samples were measured by γ-ray spectrometry using a coaxial Ge detector. The concentration of 3 elements (Co, Ni and As) in the JSS003-4, the concentration of 7 elements (Cr, Co, Ni, As, Mo, Sn and Sb) in JSS168-7 and the concentration of 7 elements (Cr, Co, Ni, As, Mo, Sb and Ta) in JSS172-7 were determined. The determined values were in good or nearly good agreement with the certified values or the reported values. The lower limit of determination values for the tramp elements were 0.01-0.1, μg/g Sb and As and 10-100 μg/g Zn and Sn respectively.