PROBLEM TO BE SOLVED: To provide a labyrinth seal device not having looseness in a sealing part due to loosening of a fastening bolt and having higher safeness without inducing a contact between a seal fin and a rotor labyrinth even when the fastening bolt fractures.;SOLUTION: A labyrinth seal device includes: a rotor labyrinth 1 having annular concave parts and annular convex parts 11, 12 formed on an outer peripheral surface along an axial direction; and a plurality of arc-shaped seal rings 2 which are annularly arranged on the inner peripheral surface of a nozzle diaphragm 5 while opposing to the above labyrinth and each of which includes a dovetail part 3 and a seal fin fixed part 4 integrally structured with the dovetail part. The seal ring 2 is configured in such a way that the dovetail part 3 is divided into three divisions with respect to the rotor axial direction, which are a center part 3a integrated with the seal fin fixed part 4, and side parts 3b, 3c fitted and fixed to both sides of the center part 3a, and that axial clearance adjusting shims 7a, 7b are inserted between the center part 3a and the side parts 3b, 3c, respectively, and integrally assembled by a fastening bolt 9.;COPYRIGHT: (C)2013,JPO&INPIT
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