For this purpose a ball-point pen and cap

摘要

The present invention provides the ballpoint pen thatprecludes the possibility of the pipe portion bending at thejoint thereof can be provided even if the outer diameter D issmall. In the ballpoint pen having a ballpoint pen tip at afront end thereof, the ballpoint pen tip rotatablyaccommodating a ball at a front end of a pipe made of metal, anoutwardly projecting pipe portion having a uniform thicknessthroughout the length thereof is arranged at a front end of theballpoint pen tip, and if a length of the pipe portion is L, anouter diameter of the pipe portion is D, a relationalexpression "L/D = 4.0" is satisfied.