A method for detecting a GPS spoofing attack using a difference between output values of a GPS receiver, which is generated due to inaccuracy of a GPS spoofer, and an apparatus therefor are provided. The method includes receiving a GPS signal; and determining the received GPS signal as a GPS satellite signal or a GPS spoofing signal using a learning model learned based on a difference between output values of a GPS receiver. The method further includes labeling and collecting dispersion degree data including a position, a speed, and a time output from the GPS receiver with whether the GPS signal is the GPS satellite signal or the GPS spoofing signal and modeling the learning model using the collected data.