An electronic shutter apparatus and light shuttering method for a still image capturing device are provided according to the invention. One embodiment of the present invention includes a single medical solution or I. The two optical members 12, 14 are arranged such that the optical fibers respectively constituting each of the optical members 12, 14 have a gap therebetween widening from the entrance end face 12a, 14a side to the exit end face 12b, 14b side.