The present invention relates to a method and system of generating a three-dimensional (3D) map. The 3D map generating method of the present invention includes: collecting spatial data and image data on a specific space by using a lidar sensor and a camera sensor that are each provided on a collecting device; estimating a movement trajectory of the lidar sensor by using the spatial data; and generating 3D structure data on the specific space based on structure-from-motion (SFM), by using the image data and the movement trajectory as input data.