Abstract: A pen with a light source has a head member with a bulb connected thereto and an adjusting assembly and batteries mounted in tube members. When the adjusting assembly is turned to adjust the position of an ink tube of the pen, the bulb in the head member is energized to allow writing in a dark place. The pen also includes an IC board mounted in an upper portion of the pen. When a push-button switch of the IC board is depressed, a light source mounted therein emits light which passes through a focusing ring above the IC board for emitting a beam of light through a hole on a top of the pen, serving as a luminous pointer.