The clamping stiffness of bolted joint is very important because it affects the fatigue stress of the bolt. But, up to now, the estimation of this stiffness has been difficult unless the joint geometry is so simple that the clamping area of the bolted members is clearly defined. However, in this paper, the authors present an analytical method to calculated the stiffnesses for two simplified models of single-bolted joints and multi-bolted joints respectively by using the three-dimensional elastic theory proposed in reference 6. That is, the abutment is assumed as a finite hollow cylinder of inner diameter 2a, outer 2b and thickness 2h which is loaded by the axial pressure on the circular band with width (c-a) around the hole. Numerical results obtained form the abutments of various values of b/a, h/a and c/a are compared with the values calculated by means of well-known F. Rotschers Effective Cone Method etc., and respective disagreements are discussed. It is sure that well-known formulas for clamping stiffness of bolted joints do not consider an exact theory of three dimensional elasticity, and generally contain many errors, then careful attention must be paid to actual applications.