Abstract: The present invention relates to a novel easily-cuttable tunnel segment structure used for the departure of a shield machine from a main tunnel to a branch tunnel or the return to the main tunnel from the branch tunnel, and provides an easily-cuttable tunnel segment structure 1 constructed by connecting a plurality of easily-cuttable tunnel segment pieces 2 in the longitudinal direction of a tunnel, wherein at least an easily-cuttable area 3 is formed by concrete 7 in which easily-cuttable reinforcement members are arranged, and a join disposed at least in the easily-cuttable area 3 in the longitudinal direction has an easily-cuttable join structure.