We propose a new method of electron spectroscopy. Using an atomic force microscope, we have measured attractive forces between a sample and a metal coated tip with varying applied voltage in dry nitrogen atmosphere. We have then plotted the values as a function of the voltage to obtain a force spectrum. The spectra of Si, ZnSe, and diamond show band gap structures which can be explained by a charge-transfer model. The spectrum of C-60 single crystal shows an energy gap of similar to 2.0 eV and a highest occupied-lowest unoccupied molecular orbital (HOMO-LUMO) separation of 3.8 eV. These results are in good agreement with the energy gap and the HOMO-LUMO separation obtained by electron spectroscopy, respectively. The spectrum of C-60 also reveals the features of density of state, which are in fairly good agreement with those obtained by electron spectroscopy. Application of this method to anthracene and p-terphenyl single crystals allowed us to discuss the natures of valence and conduction bands.