A water-soluble protein, ferritin, on a silicon surface has been imaged in pure water at room temperature with the atomic force microscope (AFM). The samples were prepared by binding ferritin molecules electrostatically to a charged polypeptide layer of poly-l-benzyl-L-histidine (PBLH). The hexagonal arrangement of ferritin molecules was imaged with high reproducibility, since the force between tip and the sample surface could be kept sufficiently lower than 10-10 N. The applied force can be stabilized and weakened mainly due to a “self-screening effect” of the surface charges of the ferritin-PBLH layer. We demonstrate that the electrostatic-binding sample preparation is one of the suitable methods for soft biological specimens to achieve the nondestructive. low-force AFM imagings.