A coolant-hole equipped drill comprising: a drill main body which is adapted to rotate around an axis line and is formed of cemented carbide; a cutting edge portion which has a tip flank formed at a tip side of the drill main body; a chip discharging groove which is opened at the tip flank on an outer circumference of the cutting edge portion to extend to the base end of the drill main body while being twisted around the axis line and provided with a front groove wall surface facing forward in a rotating direction of the drill main body and a rear groove wall surface facing backward in the rotating direction; a cutting edge which is formed at a ridge line portion where the front groove wall surface of the chip discharging groove and the tip flank of the cutting edge portion intersect with each other; a land portion which is formed between the chip discharging grooves adjacent to each other in the rotating direction at the cutting edge portion; and a coolant hole which is bored at the land portion so as to be opened at the tip flank and which extends to the base end of the drill main body while being twisted around the axis line and twisted parallel to the chip discharging groove and, wherein the coolant hole includes: a front hole wall surface which is positioned forward in the rotating direction and constant in interval with the front groove wall surface of the chip discharging groove; and a rear hole wall surface which is positioned backward in the rotating direction and constant in interval with the rear groove wall surface of the chip discharging groove; characterised in that the coolant hole further includes: an outer-circumference hole wall surface which is positioned on the outer circumferential side of the drill main body and constant in interval with the outer-circumference wall surface of the land portion. a drill main body which is adapted to rotate around an axis line and is formed of cemented carbide; a cutting edge portion which has a tip flank formed at a tip side of the drill main body; a chip discharging groove which is opened at the tip flank on an outer circumference of the cutting edge portion to extend to the base end of the drill main body while being twisted around the axis line and provided with a front groove wall surface facing forward in a rotating direction of the drill main body and a rear groove wall surface facing backward in the rotating direction; a cutting edge which is formed at a ridge line portion where the front groove wall surface of the chip discharging groove and the tip flank of the cutting edge portion intersect with each other; a land portion which is formed between the chip discharging grooves adjacent to each other in the rotating direction at the cutting edge portion; and a coolant hole which is bored at the land portion so as to be opened at the tip flank and which extends to the base end of the drill main body while being twisted around the axis line and twisted parallel to the chip discharging groove and, wherein the coolant hole includes: a front hole wall surface which is positioned forward in the rotating direction and constant in interval with the front groove wall surface of the chip discharging groove; and a rear hole wall surface which is positioned backward in the rotating direction and constant in interval with the rear groove wall surface of the chip discharging groove; characterised in that the coolant hole further includes: an outer-circumference hole wall surface which is positioned on the outer circumferential side of the drill main body and constant in interval with the outer-circumference wall surface of the land portion. a front hole wall surface which is positioned forward in the rotating direction and constant in interval with the front groove wall surface of the chip discharging groove; and a rear hole wall surface which is positioned backward in the rotating direction and constant in interval with the rear groove wall surface of the chip discharging groove; characterised in that the coolant hole further includes: an outer-circumference hole wall surface which is positioned on the outer circumferential side of the drill main body and constant in interval with the outer-circumference wall surface of the land portion.