A writing tool comprising: a barrel formed of a front barrel and a rear barrel, the front barrel comprising a distal end reduced in diameter to form a conical shape and having a distal end opening, the rear barrel comprising a plurality of guiding slits and accommodating an inner tubular member; and a plurality of refills, each refill comprising: an ink containing tube that is made from a resin material and formed in a straight cylindrical shape; and a writing tip which is attached to an end of the ink containing tube, wherein a first press-fit portion (la), of which thickness is made thickened toward an inner circumferential surface and which has an opening hole penetrating therethrough in an axial direction at a central portion of the press-fit portion (la), is formed at a front end of the ink containing tube, and wherein the writing tip or a relay member supporting the writing tip is press-fitted and attached to the first press-fit portion (la), wherein the plurality of refills is housed in the barrel (21; 22); wherein each of the writing tips is configured to alternately protrude and retract through a distal end opening of the barrel, characterized in that a second press-fit portion, of which thickness is made thickened toward an inner circumferential surface and which has an opening hole penetrating therethrough in an axial direction at a central portion of the press-fit portion, is formed at a rear end of the ink containing tube, wherein the first press-fit portion (la) and the second press-fit portion are integrally formed with the ink containing tube; and a front end of a slider is mounted and attached to the second press-fit portion of the ink containing tube, wherein an operating portion is formed on the slider and is disposed in one of the guiding slits so as to protrude to the outside of the rear barrel and be slidable in an axial direction, and wherein a return spring is disposed so as to surround the ink containing tube and the corresponding slider. a barrel formed of a front barrel and a rear barrel, the front barrel comprising a distal end reduced in diameter to form a conical shape and having a distal end opening, the rear barrel comprising a plurality of guiding slits and accommodating an inner tubular member; and a plurality of refills, each refill comprising: an ink containing tube that is made from a resin material and formed in a straight cylindrical shape; and a writing tip which is attached to an end of the ink containing tube, wherein a first press-fit portion (la), of which thickness is made thickened toward an inner circumferential surface and which has an opening hole penetrating therethrough in an axial direction at a central portion of the press-fit portion (la), is formed at a front end of the ink containing tube, and wherein the writing tip or a relay member supporting the writing tip is press-fitted and attached to the first press-fit portion (la), wherein the plurality of refills is housed in the barrel (21; 22); wherein each of the writing tips is configured to alternately protrude and retract through a distal end opening of the barrel, characterized in that a second press-fit portion, of which thickness is made thickened toward an inner circumferential surface and which has an opening hole penetrating therethrough in an axial direction at a central portion of the press-fit portion, is formed at a rear end of the ink containing tube, wherein the first press-fit portion (la) and the second press-fit portion are integrally formed with the ink containing tube; and a front end of a slider is mounted and attached to the second press-fit portion of the ink containing tube, wherein an operating portion is formed on the slider and is disposed in one of the guiding slits so as to protrude to the outside of the rear barrel and be slidable in an axial direction, and wherein a return spring is disposed so as to surround the ink containing tube and the corresponding slider. an ink containing tube that is made from a resin material and formed in a straight cylindrical shape; and a writing tip which is attached to an end of the ink containing tube, wherein a first press-fit portion (la), of which thickness is made thickened toward an inner circumferential surface and which has an opening hole penetrating therethrough in an axial direction at a central portion of the press-fit portion (la), is formed at a front end of the ink containing tube, and wherein the writing tip or a relay member supporting the writing tip is press-fitted and attached to the first press-fit portion (la), wherein the plurality of refills is housed in the barrel (21; 22); wherein each of the writing tips is configured to alternately protrude and retract through a distal end opening of the barrel, characterized in that a second press-fit portion, of which thickness is made thickened toward an inner circumferential surface and which has an opening hole penetrating therethrough in an axial direction at a central portion of the press-fit portion, is formed at a rear end of the ink containing tube, wherein the first press-fit portion (la) and the second press-fit portion are integrally formed with the ink containing tube; and a front end of a slider is mounted and attached to the second press-fit portion of the ink containing tube, wherein an operating portion is formed on the slider and is disposed in one of the guiding slits so as to protrude to the outside of the rear barrel and be slidable in an axial direction, and wherein a return spring is disposed so as to surround the ink containing tube and the corresponding slider.