The paper deals with the problem of the electrical conductivity supported by the upper atmospheric ionization, to which the diurnal variation of terrestrial magnetism is attributed in the dynamo theory. Number densities of free electrons and ions and their collision frequencies are substantially important for the evaluation of the vertical distribution and integrated value of the electrical conductivity. For this purpose various elementary processes governing the ionospheric characteristics, that is, recombination, attachment, detachment and collision, are discussed on the basis of ionospheric observation with the aid of some theoretical data by other scientists. Although our present knowledges had to face some contradictions on the way of numerical estimation of necessary elements, it is indicated that the total conductivity will be about 2×1O-7e. m. u. during the daytime, with the maximum conductivity of (1.5-2.0)×10-14e. m. u. in the E-region.