Electrical conductivity caused by the charged cloud and precipitation particles in thunderstorms has been calculated. It is found that this conductivity may be 1 or perhaps 2 orders of magnitude higher than the clear air conductivity at the same altitude. Since this conductivity increases with the precipitation intensity, liquid water content, electric field, and the electrical charges on the particles, it may show large fluctuations in thunderstorms in both space and time. In spite of this high conductivity, however, it is argued that the corresponding relaxation time may not necessarily be small, being especially so for individual charged particles and for space charge regions of small dimensions. A possible reconciliation of the discrepancies in the earlier studies and the measurements has been discussed on the basis of the present results.