To suppress the quantity of emitted light from being lowered due to miniaturization of a main capacitor.

The inner diameter of a discharge tube 32 is made to be ≤1.3 mm and the charging voltage of a main capacitor 25 is made high such as 360 to 400 V so that the quantity of emitted light can be increased. The gas pressure inside the discharge tube 32 is set high such as 110 to 230 kPa and while suppressing a rush current to the discharge tube 32, damage onto the discharge tube 32 is reduced. By increasing the sealing gas pressure, the color temperature of stroboscopic light is reduced to a proper value and the picture quality of a printed photograph is improved. Since the electrostatic capacitance of the main capacitor 25 is a little from 20 to 80 μF, a charging time is shortened and a unit can be miniaturized. Further, since the discharge tube 32 is made close to a linear light source, a reflector 35 is miniaturized and light emission efficiency is improved.