To prevent an accident of staining of clothing with ink by making a locking part of a ball of a clip face a locking part provided at an opposed barrel so as to be locked, and fixing the clip so as not to release from the barrel.

A rotary cam member 37 is moved forward and rotated by a knock bar 41, and positioned at a forward position. Then, a writing tip of a ballpoint pen writing implement 1 is suitably projected from a tip port 21 to become a writing state. In the state that the writing tip is projected from the port 21, when the writing implement is intended to be attached to a breast pocket, since an edge-like locking part 32 of the ball 30 of the clip is locked to a collar locking part 35 between cams 33, the use of the clip is disturbed, and attachment to the pocket is prevented. Accordingly, attachment of the writing tip to the pocket in the state that the writing tip remains projected to contaminate clothing is prevented.