A plate with an extended surface crack under combined biaxial force and in-plane bending moment is considered. The limit load solution is first derived based on the Mises yield criterion to take account of the effect of stress parallel to the crack plane. The J values are then evaluated using elastic-plastic FE analyses and compared with the predictions of the reference stress method using the developed limit load solution. The results show that the biaxial loading effect on J estimation may be taken into account in the reference stress method if the limit load value considering the biaxial loading effect is used.