Abstract: A sign box includes a light permeable box body of V-shaped cross section, a locating block securely fastened to one side of the flat box body, a circuit board securely mounted on the locating block, the circuit board having a plurality of LEDs (light emitting diodes) respectively inserted into respective through holes at the locating block, a control circuit mounted on the circuit board to control the operation of the LEDs, a cover covered on the control circuit, the circuit board and the locating block, and a mounting frame securely mounted on the cover for securing the sign box to a support.