A wheel deceleration calculating sections individually calculate, as negative values, wheel decelerations of front and rear wheels. If, at a time when the antilock braking control for at least one of the right and left front wheels is started or at a time when the antilock braking control for at least one of the right and left rear wheels is started, (i) a maximum value of the wheel decelerations calculated by the wheel deceleration calculating sections is equal to or larger than a first predetermined value and (ii) a difference between the wheel decelerations of the right and left front wheels or the right and left rear wheels which are in an antilock braking control state is equal to or larger than a second predetermined value, a split road determining section determines that road surfaces constitute a split road.