A push-button writing instrument has a refill (5) slidably inserted in a barrel (2) and is biased toward the back end of the barrel by a spring (6). The writing instrument is provided with a refill operating mechanism (10) capable of projecting a writing tip part (4) of the refill (5) from the open front end (2a) of the barrel (2) and retracting the same into the barrel (2) when operated by exerting a pressure in the range of 500 to 800 grams to a push-button (7). The writing tip part (4) is retracted into the barrel by a distance of about 3 mm from the open front end (2a). The push-button writing instrument is able to employ a conventional refill operating mechanism. The writing tip part (4) of the writing instrument does not project from the open front end (2a) of the barrel (2) when a force on a touching level is applied to the push-button while the writing instrument is kept in a pocket or the like.