A writing instrument providing illumination includes a penholder, a pen core, a solid state lighting source module, and a rotating plate. The rotating plate connects to one end of the penholder. The solid state lighting source module is embedded in the rotating plate which can rotate to a specific angle. A battery providing electrical energy to the solid state lighting source module is arranged inside the penholder. When the rotating plate is turned to a position perpendicular to the penholder the solid state lighting source module is turned on and when the rotating plate is turned to a position adjacent to the penholder the solid state lighting source module is turned off.