WRITING INSTRUMENT

PROBLEM TO BE SOLVED: To make it possible to effectively and accurately write characters with excellent writing sense and to suppress the ink leakage or ink drip due to operating fault or a valve member by forming the section of a nib member sliding in a longitudinal direction and the nib disposing hole of the member for disposing the nib in special shapes, and preventing the rotation of the nib. SOLUTION: A nib 2 is slidably disposed while providing a slight gap in the nib disposing hole 10 of a front barrel 9. The hole 10 is formed with a protrusion 12 as a contact restricting part for the nib 2. A recess having a sliding surface 13 is formed at the sidewall of the nib 2 corresponding to the protrusion 12, and the both are not engaged with one another to restrict the rotation of the nib 2. Accordingly, in the case of writing, even if a writing pressure is applied from any direction, the nib 2 is not rotated, but slid only in the lengthwise direction. Thus, characters can be effectively and accurately written with excellent writing sense, and ink leakage or ink drip due to operating fault of a valve member can be suppressed.