Disclosed is a method and apparatus for measuring a distance to a target object by using a radar signal in an environment where an obstacle is present. The disclosed method of measuring a distance by using a radar includes: receiving a radar signal reflected from a target object by passing through a target obstacle; estimating material of the target obstacle by using an obstacle material learning result which uses a waveform of a reference radar signal, and by using a waveform of the reflected radar signal; estimating a thickness of the target obstacle by using an obstacle thickness learning result which uses a frequency feature of the reference radar signal, and by using a frequency feature of the reflected radar signal; and calculating a distance to the target object by using a permittivity according to the material of the target obstacle, and the thickness of the target obstacle.