Provided is a boring tool capable of suppressing wear of a cutting blade according to a shape of a bore to be formed in a workpiece. The tool includes a tool body to be attached to a spindle of a rotary machining tool, and a plurality of cartridges each attached to a leading end face of the tool body, having a cutting blade and being position-adjustable in a radial direction. The tool body has a coolant passage for transporting coolant along a rotational axis direction. A discharge hole for the coolant is comprised of a first discharge hole provided between the plurality of cartridges in a leading end face and a second discharge hole provided in an outer circumference of the tool body and directed toward the cutting edge of the cutting blade.