In order to examine the mechanical properties of the membrane surface of astrocytes, we observed living astrocytes by atomic force microscopy (AFM) both in contact mode and force-mapping mode. Ridge-like structures reflecting actin filaments were observed in the topographic images in contact mode, but not in force-mapping mode, using a zero-loading force. When we measured the elasticity of astrocytes, we observed that the cell membrane above the nucleus was soft and the cell membrane above the cytosol was stiff. In particular, the parts reflecting actin filaments were very stiff. This effect of actin filaments on the elasticity of astrocytes was confirmed by the loss of actin filaments after application of actin-polymerization inhibitor.