It has been found by one of the authors that the boundary integral equations for the field functions such as potential and displacement can be regularized by introduction of their relative quantity. This technique not only provides a powerful device for accurate calculation of their internal gradients but also makes it easy to derive the integral equations for their gradients on the boundary. We attempt to apply this technique to the thermal-elastic problems. The basic reqularized boundary integral equation for thermal displacement can be obtained by superposing two kinds of special solutions simultaneously into the usual boundary integral equations. Regularized internal integral equation for thermal stress, which has a different form from the known one given by Bui [1978], is also deduced. In addition to that, this approach has succeed, for the first time, in deducing the boundary integral equations for the boundary thermal stress. Some numerical analyses for two-and three-dimensional problems are shown to verify the validity of this method.