Provided are: an autonomous moving body movement assistance device which can detect the distance to an object in a blind spot; an autonomous moving body; and a map information distribution device which distributes map information to the movement assistance device or the autonomous moving body. A movement assistance device (11) comprises an output unit (15) and a detection unit (14). The output unit (15) outputs, to an autonomous moving body (1), position information of an object (4) detected in a movement environment. The autonomous moving body (1) moves in the moving environment on the basis of the distance, measured by a distance sensor (2), to the object (4) in the moving environment. The distance sensor (2) measures the distance using light emitted by the distance sensor (2) and reflected light of said light. When the distance sensor (2) measures the apparent distance to a virtual image (9) of the object (4) projected by a mirror (7) arranged in the moving environment, a detection unit (14) detects, on the basis of position information of the mirror (7), real space position information of the object (4) output to the autonomous moving body (1) by the output unit (15).