A fixture of a dental implant comprising: a fixture body in which a screw portion is formed in a spiral shape along an outer wall and an abutment insertion groove inserted with an abutment is recessed in a longitudinal direction at an upper end; an abutment rotation stopping portion which is formed in a shape in which at least a part of an inner wall of the fixture body is shape-fitted to the outer wall of the abutment and stops a relative rotation to the fixture body of the abutment; a protrusion portion which is extended upward by a predetermined length from an edge region of the inner wall of the abutment rotation stopping portion; and a tool coupling portion which is provided in the fixture body adjacently to the abutment rotation stopping portion of the abutment rotation stopping portion and detachably coupled with a rotary tool rotating the fixture body, said tool coupling portion including a groove portion which is connected to the protrusion portion and recessed by a predetermined depth toward the outer wall of the fixture body in the inner wall of the protrusion portion, characterized in that an inner wall of the abutment rotation stopping portion is formed in an octagonal shape in a circumferential direction of the fixture body, the tool coupling portion is provided in an upper region of the abutment rotation stopping portion, said tool coupling portion additionally includes the protrusion portion, the inner wall of the protrusion portion forms the same plane as the inner wall of the abutment rotation stopping portion, a length of the protrusion portion in the circumferential direction of the fixture body is smaller than a length of one side of an octagonal shape formed by the inner wall of the abutment rotation stopping portion, four protrusion portions are provided and symmetrically disposed based on a virtual central axis of the fixture body, and, in that a length of the groove portion in the circumferential direction of the fixture body is larger than a length of one side of the octagonal shape formed by the inner wall of the abutment rotation stopping portion. a fixture body in which a screw portion is formed in a spiral shape along an outer wall and an abutment insertion groove inserted with an abutment is recessed in a longitudinal direction at an upper end; an abutment rotation stopping portion which is formed in a shape in which at least a part of an inner wall of the fixture body is shape-fitted to the outer wall of the abutment and stops a relative rotation to the fixture body of the abutment; a protrusion portion which is extended upward by a predetermined length from an edge region of the inner wall of the abutment rotation stopping portion; and a tool coupling portion which is provided in the fixture body adjacently to the abutment rotation stopping portion of the abutment rotation stopping portion and detachably coupled with a rotary tool rotating the fixture body, said tool coupling portion including a groove portion which is connected to the protrusion portion and recessed by a predetermined depth toward the outer wall of the fixture body in the inner wall of the protrusion portion, characterized in that an inner wall of the abutment rotation stopping portion is formed in an octagonal shape in a circumferential direction of the fixture body, the tool coupling portion is provided in an upper region of the abutment rotation stopping portion, said tool coupling portion additionally includes the protrusion portion, the inner wall of the protrusion portion forms the same plane as the inner wall of the abutment rotation stopping portion, a length of the protrusion portion in the circumferential direction of the fixture body is smaller than a length of one side of an octagonal shape formed by the inner wall of the abutment rotation stopping portion, four protrusion portions are provided and symmetrically disposed based on a virtual central axis of the fixture body, and, in that a length of the groove portion in the circumferential direction of the fixture body is larger than a length of one side of the octagonal shape formed by the inner wall of the abutment rotation stopping portion.