There is provided a method for detecting the possibility of rollover of a vehicle, including the steps of: detecting an actual roll angular velocity of the vehicle; obtaining an actual roll angle of the vehicle; determining an actual lateral acceleration of the vehicle; providing a two-dimensional map correlating values of the roll angular velocity with values of the roll angle to define a rollover judgment threshold; changing the threshold based on the actual roll angle and the actual lateral acceleration; forming a plot of the actual roll angular velocity versus the actual roll angle on the two-dimensional map; and judging that there is a possibility that the vehicle rolls over when the plot exceeds the threshold.