A multiplex writing implement of the invention has a multiple number of writing elements, including at least one ball-point pen element which is filled up with a thixotropic water-soluble or low-viscosity oil-based ball-point ink. The ink reserving portion of the ink reservoir of the ball-point pen element is non-flexible and has a relatively large cross-section. A portion for jointing the point assembly with the ink reserving portion is formed so that the element can readily be deflected transversely with respect to the axial direction. The writing tip portions of these writing elements can selectively be projected from and retracted into the barrel front. This multiplex writing implement is able to create line traces with thick line density without causing any blobbing of ink or ink starving. It is also possible to prevent accidental ink leakage. That is, ink can be prevented from staining the barrel cylinder, user's hands, clothes etc., which would be caused by forward leakage of ink or back leakage of ink due to upward writing as well as due to impacts from being dropped or clicked. Still, the multiplex writing implement has a suitable barrel size which meets the demands for portability and high performances of handling.