To lessen a load on a reamer boring worker and to improve work efficiency.

This boring tool includes: a cylindrical body 2 abutting on a working surface W; a guide member 17 fitted and engaged with the outer periphery to cover the base end of the body part 2 and having a receiving screw at the central part; and a reamer 21 having a feed screw engaged with the receiving screw to fix an attitude vertically to the working surface W. The tip part of the body part 2 is provided with grooves 13, 14, air suction holes 4 connected from the grooves 13, 14 to the external suction means; and sealing members provided inside and outside to surround the grooves 13, 14 and the opening part of the air suction hole 4. In the boring work, after the hole position is fixed by the tip of the reamer 21, the air is discharged by the suction means to fix the body part 2 with negative pressure, and the reamer 21 is rotated to feed and bore. The position of the reamer 21 to the working surface W is fixed and the advance angle of the reamer 21 is kept vertical.