A cutting tool holder (100, 400) comprising: a tip seat, provided in a front end portion of the cutting tool holder (100, 400), for fixing a cutting tip thereto; and an ejection port opened such that a coolant can be supplied toward a cutting edge of a cutting tip fixed to the tip seat, wherein a recess surface portion is formed in a predetermined range of the lateral flank of the front end portion of the cutting tool holder (100, 400), so as to be recessed relative to a lateral flank of a rear portion rearward of the predetermined range, the tip seat includes a restraining wall extending from a front end of the tip seat toward a rear end of the tip seat opposite the lateral flank side of the tool holder such that a cutting tip fixed to the tip seat is positioned between the restraining wall and the ejection port; characterized in that: the ejection port is opened such that the coolant can be supplied from the lateral flank side of the cutting tip toward the cutting edge of the cutting tip fixed to the tip seat, the ejection port being provided at the lateral flank side of the cutting tool holder (100, 400); the recess surface portion is formed in a predetermined range from a front end toward a rear end, of the lateral flank of the front end portion of the cutting tool holder (100, 400) such that the width of the front end portion of the tool holder is smaller than that of the rear portion of the tool holder; the ejection port is provided in a frontward-facing surface in the recess surface portion such that, when the cutting tip is fixed to the tip seat, the ejection port is located at a position lower than a rake face of the cutting tip and the coolant is ejected obliquely upward. a tip seat, provided in a front end portion of the cutting tool holder (100, 400), for fixing a cutting tip thereto; and an ejection port opened such that a coolant can be supplied toward a cutting edge of a cutting tip fixed to the tip seat, wherein a recess surface portion is formed in a predetermined range of the lateral flank of the front end portion of the cutting tool holder (100, 400), so as to be recessed relative to a lateral flank of a rear portion rearward of the predetermined range, the tip seat includes a restraining wall extending from a front end of the tip seat toward a rear end of the tip seat opposite the lateral flank side of the tool holder such that a cutting tip fixed to the tip seat is positioned between the restraining wall and the ejection port; characterized in that: the ejection port is opened such that the coolant can be supplied from the lateral flank side of the cutting tip toward the cutting edge of the cutting tip fixed to the tip seat, the ejection port being provided at the lateral flank side of the cutting tool holder (100, 400); the recess surface portion is formed in a predetermined range from a front end toward a rear end, of the lateral flank of the front end portion of the cutting tool holder (100, 400) such that the width of the front end portion of the tool holder is smaller than that of the rear portion of the tool holder; the ejection port is provided in a frontward-facing surface in the recess surface portion such that, when the cutting tip is fixed to the tip seat, the ejection port is located at a position lower than a rake face of the cutting tip and the coolant is ejected obliquely upward. the ejection port is opened such that the coolant can be supplied from the lateral flank side of the cutting tip toward the cutting edge of the cutting tip fixed to the tip seat, the ejection port being provided at the lateral flank side of the cutting tool holder (100, 400); the recess surface portion is formed in a predetermined range from a front end toward a rear end, of the lateral flank of the front end portion of the cutting tool holder (100, 400) such that the width of the front end portion of the tool holder is smaller than that of the rear portion of the tool holder; the ejection port is provided in a frontward-facing surface in the recess surface portion such that, when the cutting tip is fixed to the tip seat, the ejection port is located at a position lower than a rake face of the cutting tip and the coolant is ejected obliquely upward.