To provide a writing instrument which supports a writing body slidably in an axial direction in a leading end opening of a shaft tube or a leading end opening of an end member attached to the shaft tube and which can evenly control wobbling of the writing body in whatever way held.

A writing instrument supports a slider 8 slidably in an axial direction in a leading end opening 2a of an end member 2 attached to a shaft tube 1. A flexible cylindrical member 33 molded by a resin extruded molded article, fiber bundle or sintered porous body is attached to the outer peripheral face of the slider 8 which is opposite the leading end opening 2a of the end member 2. Thereby, the cylindrical member 33 is disposed in such a state as embedded in a clearance between the end opening 2a and the outer peripheral face of the slider 8. Besides, flexibility of the cylindrical member 33 functions and allows the efficient control of wobbling caused by the clearance between the slider 8 and the end opening 2a of the end member 2.