It is possible to measure nondestructively the residual stress in the interior of the top coating in the thermal barrier coating (TBC) using hard synchrotron X-rays, which have a large penetration depth and high brightness. A new hybrid method is proposed to estimate the distribution of the spalling stress in the top coating by combining the synchrotron data with the stress data measured by the conventional X-ray method utilizing a Cr-Kalpha radiation. The new hybrid method was applied to estimate the distribution of the spalling stress in the top coating of TBC which had a zirconia top coating with a thickness of 0.24 mm and a NiCoCrAlY bond coating with a thickness of 0.2 mm. The residual stress, sigma(11)-sigma(33), within the top coating was determined by synchrotron X-rays of 73 keV energy level, where sigma(33) was the stress perpendicular to the surface and sigma(11) was an in-plane stress. The distribution of residual in-plane stresses, sigma(11) and sigma(22), in the top and the bond coating was determined with the conventional X-ray method by repeating the measurement after successive removal of the surface layer. From the data obtained by synchrotron and conventional X-rays, the distribution of stress component, sigma(33), responsible for spalling was determined. The estimated value of the spalling stress was very small beneath the surface and increased to about 75 MPa near the interface between the top and the bond coating.