Disclosed is an impact detection system including: an optical fiber including a plurality of sensor sections to reflect light, a wavelength band of the reflected light vibrates depending on an elastic wave propagating through a subject to be inspected; a light source to input light into the optical fiber; optical filters each connected to an output terminal of the optical fiber; and an arithmetic processing unit to detect the impact from output values of sensor sections, wherein the wavelength bands of the sensor sections in the optical fiber are distributed such that the vibration bands caused by the impact to be detected do not overlap with each other, and a pass band of the optical filter corresponding to one of the sensor sections is distributed in the vibration band caused by the detection object, and is distributed in both sides of a center of the wavelength band of the one sensor section.