This paper presents a stress analysis at the root of a bolt thread with pitch error or flank angle error by the finite element method and the copper-electroplating method which are the same methods as mentioned in the previous papers. Firstly, as a three dimensional axially symmetrical problems, the load distribution at the bolt thread which is screwed in a nut thread, is computed by the finite element method comfactor under this load distribution is computed. Secondly, a measuring method of the stress concentration factor by the copper-electroplating method presented in the 1st report, is applied to the bolt threads with four levels of pitch errors or four levels of flank angle errors. The obtained results are as follows : (1) The pitch error has an important effect upon the load distribution and the stress distribution along the bolt thread. Therefore, in order to reduce the stress concentration factor, it is necessary to make uniform the stress distribution at each root of bolt thread. (2) The flank angle error has a little effect upon the stress concentration factor.