An illuminating device for a wheeled vehicle, such as a bicycle, comprising a light housing and a battery case pivotally secured to one another by means including a pair of branched arm portions so that vertical angle of the position of said light housing can be adjusted. Metallic terminals for positive and negative current are provided in a battery case to press and hold batteries therein and the respective ends thereof extend from the battery case along the inner sides of the arm portions. Metallic terminals for positive and negative current in the light housing extend to a base portion of the light housing in through holes in the base portion. An electrical connection is made between the respective terminals in the light housing and the battery case by means of a pair of washers, each having a projection thereon fixed between the inner sides of the arm portions and the outer sides of the base portion. Bolt means extend through aligned openings in the arm portions, base portion and washers for pressing the parts together to retain the light housing and battery case in adjusted position and for making a firm electrical connection between the respective terminals in the battery case and the light housing and the washers.