The crack initiation and propagation behaviors in the γ’-Fe4N layer on the nitride steel subjected to monotonic and cyclic deformations were revealed. In the case of the monotonic test, cracks initiated from the γ’ layer/matrix boundary and propagated along grain boundaries and within grains on {001}γ’. Those cracks should be generated by the stress concentration at the γ’ layer/matrix boundary because the strain concentration at the boundary was detected. While, in the case of the cyclic tensile test, cracks initiated from the voids at the surface and propagated along grain boundaries and within grains on {111}γ’. Slip trace analysis revealed that the slip system of γ’ is identical with that in general fcc metals, that is, {11-1}<011>. Therefore, the cracks within γ’ grains should initiate and propagate through slipping-off mechanism, which is observed in the high nitrogen austenitic steel.