The invention relates to a writing utensil comprising a shaft (9) and an especially single-piece push-button element (K, L; 10). Said push-button element comprises a push-button section (L), a base section (K, 50), and an actuation rod section (S) that extends from the base section in the axial direction. An actuation tooth (Z) radially projects from said actuation rod section and is displaced within the shaft (9), especially in the peripheral, tangential and/or radial direction by means of at least one small segment (A, B) of the shaft (9) that is deformed in the radial direction when the push-button element (10) is actuated. Said push-button element may assume two axially spaced apart stable positions that correspond to the writing position and the retracted position of the writing utensil. The actuation tooth (Z) takes the same at least peripheral (tangential) position in both positions, however, axially displaced. The actuation tooth is mounted on the actuation rod section in such a manner and has such a peripheral (tangential) extension (z6, z2) and shape that a center plane (70) that extends parallel to a central axis (100) of the push-button element also extends in an axial front section (z3, z1) and in an axial rear end section (z7) of the actuation tooth (Z) within the actuation tooth. The invention provides a single-piece mechanism, combined with a substantially single-piece shaft (at least in the rear section) which is inexpensive in production, is functionally reliable and requires as few parts as possible.