1. A method for detecting a road environment based on a frequency modulated continuous wave (FMCW) radar, the method comprising the steps of: the FMCW radar performing a first scan to acquire a first frequency spectrum of beat signals, and shifting the first frequency spectrum based on first velocity information of a vehicle on performing the first scan; the FMCW radar performing a second scan to acquire a second frequency spectrum of beat signals, and shifting the second frequency spectrum based on second velocity information of the vehicle on performing the second scan; acquiring correlation information between the shifted first frequency spectrum and the shifted second frequency spectrum; and comparing the correlation information with a set threshold value and detecting the road environment.