An LED filament includes LED chips in an array, two conductive electrodes, conductive wires, an enclosure coating, and an auxiliary piece. The chips are connected with one another. The electrodes are corresponding to the chips. Each electrode is connected to a corresponding LED chip at an end of the array. The wires connect the chips and the electrodes. The wires are respectively between every two adjacent chips and between each of the electrodes and the corresponding chip at an end of the array. The coating is on two or more sides of the array and the two electrodes. A portion of each of the electrodes is exposed from the coating. The auxiliary piece is in the coating and overlaps one of the wires between each of the electrodes and the corresponding one of the two chips respectively at two ends of the array on a radial direction of the filament.