Facility diagnosis system

This facility diagnosis system is provided with an imaging unit, a position measurement unit, an encoding unit, an image selection unit, and an image comparison unit. The imaging unit is provided in a railway vehicle and images a railway facility provided along a travel path of the railway vehicle. The position measuring unit measures the vehicle position of a traveling railway vehicle. The encoding unit associates the moving image captured by the imaging unit with the vehicle position, and encodes the moving image. The image selection unit selects, on the basis of a first vehicle position associated with the first moving image, a selection image of a railway facility to be diagnosed from among encoded moving images stored in advance in the moving image storage unit in association with the vehicle position. The image comparison unit calculates a motion vector between a first image included in the decoded first moving image and a second image included in the decoded second moving image, and diagnoses an abnorm