The iron powder was sintered in order to study the kinetics and the mechanism of sintering by measuring shrinkage rate of iron compact and by its subsequent microscopic examination. According to the experimental results, grain growth and pore shape in the compact clearly indicate that volume diffusion is the predominant mechanism in sintering of iron powder in the α-region. On the other hand, the apparent density of sintered compact is substantially independent of sintering temperature and time in the γ-region, and therefore it seems that the volume diffusion does not play an important role in this region.