Abstract: A method of producing a light conductive plate type light source, at least one light diffusing plate and a light reflecting plate are placed on the opposite illuminating surfaces of a light conductive plate in the overlapped state, and subsequently, a plurality of fixing members are press-fitted into the light conductive plate through the light diffusing plate and/or through the light reflecting plate with the aid of supersonic vibration applied to each fixing member. Thus, a securing operation can be achieved for the light conductive type light source at a remarkably improved efficiency regardless of the number of light diffusing plates to be placed on the light conductive plate in the overlapped state. In addition, the light conductive type light source can be produced at a reduced cost because no double-sided adhesive tape is required, and moreover, no supersonic welding operation is performed for each plate.