An illumination device comprises a holder, a plurality of light emitting elements, a translucent cover and a lamp cap structure. The holder comprises a heat dissipating base body and a carrying unit. The carrying unit is connected to a top portion of the heat dissipating base body and comprises a carrying base body, a circuit pattern and a heat dissipating pattern, the circuit pattern and the heat dissipating pattern are directly formed to a surface of the carrying base body, the circuit pattern has a plurality of mounting positions, the heat dissipating pattern at least extends from a region close to the mounting position to a region where the heat dissipating pattern can contact the heat dissipating base body. The plurality of light emitting elements are respectively provided at the plurality of the mounting positions and establish an electrical connection with the circuit pattern.