In this study, the energy release rate is derived for interface debonding cracks in ceramic-matrix composites, using approximate solutions of an axisymmetric cylindrical fiber-matrix model. The energy release rate expression includes the important effects of compressive residual stresses and frictional sliding stress on the debonded interface in a closed-form equation. A parametric study of the energy release rate is carried out and the effects of various parameters on the energy release rate are clarified and compared with results of other studies. The method to determine the critical debonding length is proposed based on the energy release rate and the fracture criterion of the interface and fiber. The predicted debonding length gives good agreement with published experimental results.