To make the device small in size and light in weight by providing a cathode-ray tube to a folded part formed by folding a part at an end or at both ends contributing to light emission or a part not contributing to light emission.

A straight fluorescent tube 1 having a part 1a folded at both ends in a nearly L-shapes is provided. The fluorescent tube 1 lights an area of nearly as long as the fluorescent tube 1 at a position representing a position L1 with a uniform light quantity. In general, the luminous intensity of a fluorescent tube is weakened around electrodes at both ends. Thus, when the straight fluorescent tube is illuminating an object with a uniform luminous intensity, the light from both ends of the fluorescent tube with weak luminous intensity cannot be used and only the middle part of the fluorescent tube is used, and then there is a problem the width of the lighting device must be large with respect to the width of a valid lighting area. However, in the fluorescent tube 1 with the folded part 1a, the width of the lighting device is smaller than the width of the valid lighting area by folding both ends with weak luminous intensity nearly in an L-shapes.