An elevator system, comprising; a hoistway; an elevator controller; an abnormal condition detection device; and a governor having a governor rope wrapped around a governor sheave and a tension sheave; and characterized in that the abnormal condition detection device comprises: a plurality of TOF cameras each disposed at different heights in the hoistway and configured to monitor rope sway of the governor rope and capture an image of the governor rope at each height of the TOF cameras, the image including image data and distance data of the governor rope; and a rope sway detector controller connected to the TOF cameras for detecting rope sway of the governor rope and transmitting an abnormal condition detection signal to the elevator controller, wherein the rope sway detector controller is configured to detect an abnormal condition of the governor rope by estimating a maximum amplitude of the governor rope based on a vibration mode of the governor rope and amplitude of the governor rope at each height of the TOF cameras, and the vibration mode of the governor rope is calculated from amplitude changes of the governor rope at each height of the TOF cameras in time series. a hoistway; an elevator controller; an abnormal condition detection device; and a governor having a governor rope wrapped around a governor sheave and a tension sheave; and characterized in that the abnormal condition detection device comprises: a plurality of TOF cameras each disposed at different heights in the hoistway and configured to monitor rope sway of the governor rope and capture an image of the governor rope at each height of the TOF cameras, the image including image data and distance data of the governor rope; and a rope sway detector controller connected to the TOF cameras for detecting rope sway of the governor rope and transmitting an abnormal condition detection signal to the elevator controller, wherein the rope sway detector controller is configured to detect an abnormal condition of the governor rope by estimating a maximum amplitude of the governor rope based on a vibration mode of the governor rope and amplitude of the governor rope at each height of the TOF cameras, and the vibration mode of the governor rope is calculated from amplitude changes of the governor rope at each height of the TOF cameras in time series. a plurality of TOF cameras each disposed at different heights in the hoistway and configured to monitor rope sway of the governor rope and capture an image of the governor rope at each height of the TOF cameras, the image including image data and distance data of the governor rope; and a rope sway detector controller connected to the TOF cameras for detecting rope sway of the governor rope and transmitting an abnormal condition detection signal to the elevator controller, wherein the rope sway detector controller is configured to detect an abnormal condition of the governor rope by estimating a maximum amplitude of the governor rope based on a vibration mode of the governor rope and amplitude of the governor rope at each height of the TOF cameras, and the vibration mode of the governor rope is calculated from amplitude changes of the governor rope at each height of the TOF cameras in time series.