To provide a writing instrument capable of further improving durability of a writing nib without impairing writing performance even when writing is performed with a heavy writing load. A writing instrument A having a writing part formed of at least a writing nib 30 made of a porous body and a retainer 40 made of a hard material, in which the protrusion amount of the distal end of the writing nib 30 from the retainer 40 is 0.65 mm or more and 1.05 mm or less and/or 40% or more and 65% or less of the thickness of the writing nib 30.