An elevator rope elongation measuring device provided with: a camera for photographing one or a plurality of elevator ropes R; and an image processing unit for image processing a photographed image output from the camera, wherein: the image processing unit detects an external form portion of the elevator rope R as a regular hill and valley shape T, converts a cyclic length of the hill and valley shape into actual dimensions and makes this a measured value, and finds a ratio of the measured value with respect to a standard value prescribed for the elevator rope as an elongation, therefore attaining the effect of making it unnecessary to have a preliminary installation of a sensor or marker to the rope, or preliminary creation of a database.