To provide a safety device inexpensively preventing an accident when using an escalator.

This safety device includes a plurality of cameras 2 for photographing a specific area 20 with the outside from a moving handrail 51 of the escalator 5 as the center, a storage part 15 for storing a reference image of the specific area 20, an image recognizing part 11 for extracting difference data between a present image of the area and the reference image by respectively receiving image data from the plurality of cameras 2, an abnormality determining part 12 for discriminating whether or not to be an abnormal state from the difference data, a warning part 13 for generating a warning when the abnormality determining means determines as an abnormal state, and a forced stopping part 14 for stopping the escalator 5 when the abnormality determining part 12 determines as the abnormal state.