Long-lived residual radioactivity 63Ni produced by the (n, y) reaction was detected for the first time from a steel plate sampled at near the hypocenter of the Hiroshima atomic bomb. Nickel and cobalt were chemically separated and enriched from the steel sample. Low energy beta rays of 63Ni were measured with a low-background liquid scintillation counter and gamma-rays of 60Co were measured with a low background Ge detector. Specific activities were determined as 0.0063±0.0004 Bq mg-1 for 63Ni/Ni and 8.70±0.46 Bq mg-1 for 60Co/Co at the time of the bomb explosion. Comparisons with the calculated yield based on the current dosimetry system DS86 neutrons were also given.