To provide a sterilization device capable of actively utilizing the sunlight of high safety indoors or the like while it is known from long before that the sunlight is provided with the sterilization function of molds or the like.

The one end sides of many optical fibers are bundled to one, an end face 12 is turned to the light receiving end of the sunlight and the other end sides are divided into four or more, bundled and respectively used for the irradiation ends of the sunlight. The condensing lens 28 of the sunlight is attached through a holder 22 to the end face 12 on the light receiving end side, the holder is provided with an adjustment mechanism 32 for adjusting the distance of the light receiving end face 12 and the condensing lens 28 and varying a sunlight condensing density and the diaphragm mechanism 36 of light quantity propagated through an optical fiber bundle 10, an irradiation amount from the irradiation end is made adjustable by increase and decrease corresponding to seasons and weather or the like and sterilization power is adjusted. Also, a stand 46 is provided on the light receiving end side and the light receiving end face is easily held towards the sun.