A light bulb includes a bulb body, a light guide, and at least one light-emitting diode (LED). The bulb body includes a light-transmitting shell and a conductive base. The light-transmitting shell is mounted to the base. A circuit board is fixed at one side of the base and is in electrical connection with the base. The LED is mounted to the circuit board that is arranged at one side of the base, and the LED is in electrical connection with the circuit board to provide an internal light source. The light guide is arranged inside the bulb body and has an end forming a cavity that receives the LED therein, whereby the light guide is set erect on the base. As such, advantages of easy manufacturing, reduced costs, operation safety, increased angular range of illumination, and extended lifespan can be provided.