Provided is a ballpoint pen having a simple structure and which is capable of writing lines having different widths, using one writing tip and without using any particular operation during writing. Also provided is a ballpoint pen capable of writing lines having different widths, with a single writing ball by using two writing portions. An outer member (50) covering the outer circumference of a holder (21) covers a section that reaches as far as a narrowed section (23) of the holder (21) and has an outer member tip end portion (51) capable of coming in contact with a writing surface at the same time that the writing ball (30) does. An ink is used that is capable of spreading between the writing ball (30) and the contact section of the writing surface and between the outer member tip end portion (51) and the contact section of the writing surface, in a state in which the writing ball (30) and the outer member tip end portion (51) are in contact with the writing surface at the same time. In addition, the relative position of the outer member (50) and the holder (21) can be changed to a holder retracted position and a holder protruding position. When the relative position is in the holder retracted position, the writing ball (30) and the tip section of the outer member (50) can be in contact with the writing surface at the same time.