WRITING INSTRUMENT, PARTICULARLY A BALLPOINT PEN

A writing instrument (1), particularly a ballpoint pen, comprising a sleeve-like housing (2), a reservoir (3) axially extending in said housing (2), a push button (6) positioned in the rear portion of the housing (2) and mounted in the housing (2) to be manually displaceable in a fashion to be secured against pivoting with the reservoir (3) between a rear parking position and a front writing position and biased in its parking position by the force of a spring a latching device (19) for latching the push button (6) in its writing position with a latch recess (21) in the housing (2) and a latch lug (23) positioned at the free end of a transversely elastically bendable spring arm (24) extending from the push button (6), a shift device (35) for releasing the latching device (19) and returning the latch lug (23) into its parking position, and a support member (17b) disposed at the push button (6) and comprising a support surface (17b) which bars the latch lug (23) by a stop from lateral movement into the latch recess (21) when being moved back from a position moved forwards beyond the writing position. In order to enhance the arrangement of the support member (17) in the writing instrument (1), the support member (17) is disposed at a peripheral wall portion (17a) of the push button (6), which is located radially outside a central free space (12) in the push button (6).