Thermal stress distribution and the strength of the joint due to thermal stress were examined when butt adhesive joints having circular hole defects in an adhesive were in the steady-state temperature distribution. In the analyses, the thermal stress distrbution in the adhesive was given using the two-dimensional theory of elasticity in the case that adherends of similar size and material were kept at constant temperature and side surfaces of the joint were surrounded wich fluid of different temperature. The effects of the location and the size of hole defects on the thermal stress distrbution were clarified by numerical calculations. Then, comparing the principal stress at the periphery of a hole with that at the interface between an adherend and an adhesive, the strength of the joint due to thermal stress was discussed. For verification, photoelastic experiments were performed, and the analytical result was found to be in fairly good agreement with the experimental one.