The kinematics, statics and stiffness effect of a 3D grasp by a multifingered hand is investigated considering the rolling contact at the fingertip. By representing the local shape of the fingertip and the object by a quadratic surface and by linearization of the fundamental formulae, the kinematic-static relation for the motion-force of the fingertip, contact location and the object is derived. Additionally, the stiffness effect for object motion caused by the change of the contact force and the contact location at the fingertip is analyzed. The influence of the stiffness effect on the stability of the grasp is quantitatively evaluated for the grasp by a three-fingered hand.