The down sizing of devices has been so rapidly promoted that the device and the circuit feature size will break into the nanometer range less than 1000 A˚ at the beginning of the next century. It is of critical importance to investigate the characteristics of microstructure capacitances for analysis of future devices and circuits. We analyze the general features of microstructure capacitance based on the self‐consistent field approximation, and clarify that it is decomposed into three components. One is the extension of the capacitance of classical perfect conductors discussed in electrostatics. The quantum‐mechanical effect plays an important role in the other two components; one of them is proportional to the electronic density of states at the Fermi potential of the conductor in low temperatures. At room temperature this portion is proportional to the electronic charge in the conductor. The other is due to the delocalization of electronic charge off the surface into the bulk of conductor. These two components have only self‐capacitance contributions. Various aspects of the microstructure capacitance, e.g., the order of magnitude, the diagrammatic expression, the charging energy, and the quantum dot charging are discussed. ©1995 American Institute of Physics.