BORING DEVICE

PROBLEM TO BE SOLVED: To provide a boring device used, for example, for a long tip supporting construction method which is one of the auxiliary construction methods used in tunnel driving capable of efficiently burying a buried pipe in a hole while the hole is bored simultaneously and also easily and assuredly recovering a boring rod from the hole. SOLUTION: A boring device comprises a boring inner bit 4 installed supportedly at the tip part of a boring rod 5, a boring ring bit 1 disposed on the outer periphery of the inner bit, and a buried pipe 3 buried in a hole bored with these both bits 1 and 4. A recess and projection engaging part 44 which is engaged when the inner bit 4 is rotated relatively in the rotating direction for boring in the ring bit 1 and disengaged when it is rotated relatively in the direction reverse to that rotating direction for boring is provided between these both bits 1 and 4. Then, provided are means 14 and 21 for rotation- stopping and locking the ring bit 1 to a buried pipe 3 when the engagement of the recess and projection engaging part 44 is disengaged and a contact engaging part 4d to pull in the buried pipe 3 into the hole interlockingly with the moving operation of the inner bit at the time of boring.