Abstract: A cutting tip 14 is secured to the distal end of the shank 12 of a non-core type bit 16 that is designed to bore holes. The shank 12 has a water-supplying passage 22 and a water-discharging passage 26. The water-supplying passage 22 is configured to supply cooling water to the tip 14. The water-discharging passage 26 is configured to discharge the cooling water from a hole 24 being bored by the tip 14. A swivel 32 has a water-supplying port 28 that is connected to a cooling-water source 54. The cooling water flows from the cooling-water source 54 to the bit 14 through the water-supplying passage 22. A suction force applied by a cooling-water discharging means 56 compels the cooling water out of the hole 24. The cooling water is thereby discharged through the water-discharging passage 26.