Japan Welding Engineering Society (JWES) standard WES2805, which is based on an elastic-plastic fracture mechanics (CTOD design curve approach), has been widely used to evaluate fracture safety of structures. And work on revision to the standard is now underway so that it can take into account the recent advances in fracture mechanics treatments. On the other hand, U. K. CEGB R6 approach has lately attracted considerable attention. The notable feature of the R6 is that the approach interpolates between two criteria, that is, LEFM failure and plastic collapse. Although the basis of the approach can be formulated by an elastic-plastic J analysis, it simply needs stress intensity factor and limit load in an assessment, and this point is considered as an advantage for its application. In this study, the validity and accuracy of the fracture assessment of JWES and R6 for the situation where brittle fracture occurs from a defect at a structural stress concentration are investigated. These two approaches are applied to four types of structural model test which were carried out in Japan. The investigation includes examination of conservatism and discussion on the relation of the two methods.