ROAD INCLINATION ESTIMATING APPARATUS OF VEHICLE

A road inclination estimating apparatus is configured to acquire power spectrum density of vertical vibration by a frequency analysis based on the detected vertical acceleration of the sprung mass of a vehicle. The apparatus is configured to determine that a first estimation condition is satisfied, when the power spectrum density has two of the acquired peak frequencies, wherein, one of the two of the peak frequencies is within a predetermined first frequency range, and the other one of the two of the peak frequencies is within a predetermined second frequency range.