Abstract: A motor vehicle neon lamp device for illuminating the number plate of a motor vehicle, including a transparent plastic lamp shade sealed by a rubber packing to hold a neon tube on the inside and a power transformer on the outside in a flush manner. The lamp shade has input and output electrodes fastened inside a transformer chamber thereof and respectively connected to the battery power supply of the motor vehicle and the neon tube, which are electrically connected as the power transformer is inserted in the transformer chamber on the lamp shade.