The orientation relationship between ferrite and (Fe,Mn)3AlC has been investigated in an Fe-3.5Mn-5.8Al-1.05C based eutectoid alloy. Electron diffraction pattern analysis shows two possible orientation relationships between both phases. Accurate analysis using convergent beam electron diffraction reveals the deviation of pole from pole in Nishiyama-Wasserman orientation relationship and the coincidence of and poles in Kurdjumov-Sachs orientation relationship. Transmission Kikuchi diffraction resolves the orientation of several tens nanometer scales of ferrite+(Fe,Mn)3AlC lamellar. Kurdjumov-Sachs orientation relationship between ferrite and (Fe,Mn)3AlC is clarified by the comparison of deviation angle from both orientation relationships. Coherency at the interphase boundaries is further discussed.