In an idealized 2-dimensional crack, the deformation constraint is kept constant along the crack front line. Thus it is expected that the fracture mode is also kept constant along the crack front. However, the deformation constraint and fracture mode change generally along the crack front line in a 3-dimensional crack, and this deformation mode change cannot be dealt with as far as conventional parameters such as K or J are applied. The CED (Crack Energy Density) was proposed as a parameter which has no restriction on the constitutive equation and is expected to be applicable to almost all kinds of crack problems. This paper purports to demonstrate that the deformation mode change above can be evaluated quantitatively when the CED is applied.