To provide a tail clearance measurement device capable of improving measurement accuracy of a tail clearance even when performing non-contact measurement in an internal environment of a shield machine.SOLUTION: A tail clearance measurement device 100 according to the present invention, comprises a measuring unit 10 and a control unit. The measuring unit includes: a non-contact type distance sensor disposed on an inner peripheral side more than an inner surface 2 of a segment 1; a rotation mechanism for rotating a distance sensor in a plane along the digging direction and the radial direction of a shield digging machine 200; and rotation detection parts for detecting a rotation position of the distance sensor by the rotation mechanism. The control unit calculates a tail clearance Δ on the basis of measurement results at a plurality of points on the inner surface 2 of the segment 1 and measurement results at a plurality of points on an inner surface 102 of a skin plate 101 among the measurement results at the plurality of rotation positions of the distance sensor, and a thickness B of the segment 1.SELECTED DRAWING: Figure 1
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