An illumination device using LEDs (101) has a circuit board and a plurality of LEDs disposed on the circuit board elements. The circuit board can be obtained by assembling a plurality of the circuit board elements (11) together. The circuit board element comprises a board (110) and an electric trace (1151) attached to the board. The board comprises a plurality of connecting units (111, 112, 113, 114) formed at lateral sides thereof. The circuit board element connects with an adjacent circuit board element via the connecting units. The electric trace extends from the board to the connecting units and electrically connects with the electric trace of the adjacent circuit board element.