TUNNEL BORING MACHINE

PROBLEM TO BE SOLVED: To improve water-proofness in a tunnel boring machine by certainly preventing water from entering the inside of the boring machine body even when widening. SOLUTION: A main cutter mechanism 11 is attached to an front end of a main boring machine body 12, and a boring machine body 14 is provided on the excavating direction sides of the main boring machine body 12, and a subcutter mechanism 13 is attached to its front end, and a support shaft 53 of each subboring machine body 14 is movably fitted in a slot 52 of the main boring machine body 12, and two widening jacks 16 are erected to make the subboring machine body 14 horizontally movable and turnable to the main boring machine body 12. A main tail seal 66 stuck fast to the rear of the main boring machine body 12 and a subtail seal 67 stuck fast to the rear of the boring machine body 14 are shifted back and forth to about rectangularly pile up a piled up part 67a where the end of the subtail seal 67 turns forward on the main tail seal 66.