Ballpoint pen and cap therefor.

摘要

The present invention provides the ballpoint pen (1) with which the possibility of the pipe portion bending at the joint thereof is prevented even if the outer diameter D is small. The ballpoint pen has a ballpoint pen tip (2) at a front end thereof, the ballpoint pen tip (2) rotatably accommodating a ball (22) at a front end of a pipe (21) made of metal, and an outwardly projecting pipe portion (3) of the pipe having a uniform thickness throughout the length thereof is arranged at a front end of the ballpoint pen tip (2). If a length of the pipe portion (3) is L, an outer diameter of the pipe portion is D, a relational expression "L/D </= 4.0" is satisfied. <IMAGE>