The micromagnetic distribution of the clusters of the PPH-FeSO4 complex (Schiff-base polymer with sulfate iron) was investigated by magnetic force microscopy (MFM). MFM results exhibited that magnetites (Fe3O4) were irregularly included in PPH-FeSO, complexes. Some nanocrystalline Fe3O4 magnetites aggregated and formed magnetic clusters of 50-140 nm length. The ferromagnetic properties of the PPH-FeSO4 complex were associated with the existence of Fe3O4 magnetites. Moreover, the influence of the distance between tip and sample surface on the MFM images was also discussed. The observation suggested that MFM was a very useful tool for studying the micromagnetic structure of organic ferromagnets.