To provide a writing implement which can make a sufficient light for writing in the dark.

In the present optical fiber pen, a light-emitting diode is embedded in the main body of the pen, or a cut part 4 of the material for fitting the light-emitting diode is provided in the head (opposite end to a penpoint) of the main body, in order to pass the light through a transparent material of the main body of the pen. A pattern 5 of indentation is provided in a part of the main body, and the internal surface of the main body is subjected to specular finish, or a material having a high reflectance (such as an aluminum leaf) is wound on the surface of a refill, while a lithium cell fitting part 3 is provided in the head of the pen.