To provide a writing instrument which can more easily operate the switching operation for writing utensils to solve the problem that in a composite writing instrument for which a plurality of writing utensils are housed in one barrel, every time when the writing utensil is selected, an operation such as depressing a protuberance section on the upper end of the barrel, or turning a rotating section which is provided on the barrel is required, and when the writing instrument is used while frequently switching the writing utensils, there is a tendency that the operation becomes an obstacle for the thinking at the time of writing or reading.

Three kinds of writing utensils are fixed in such a manner that respective distal ends are located on a flat surface forming a regular triangle of which each edge is 5 mm or lower. Then, a range in which the barrel is gripped with fingers is formed into an approximately regular triangle cross section which is shifted at 60° from the regular triangle formed by the distal ends. Thus, the kind of a presently selected writing utensil can be discriminated visually or by the feeling for this composite writing instrument.