An LED bulb comprises a lamp housing, a lamp cap, a core tube disposed inside the lamp housing, a plurality of LED plates mounted on the core tube, and a controller serving to manipulate an on-off operation of the LED plates. Wherein, the controller is substantially disposed inside a room of the core tube, and the core tube has one end thereof connected to the lamp cap, so as to facilitate a free substitution of the controller and promote the using convenience. The connection of the core tube and the lamp cap serves to radiate the thermal created by the LED plates from the core tube toward the lamp cap and the lamp housing for a speedy dissipation and preventing from burning the LED bulb under a high temperature.