An apparatus for estimating tire wear amount comprising: a vehicle longitudinal acceleration measuring unit installed to a vehicle body side of a vehicle and measuring longitudinal acceleration of the driven vehicle; and a wheel rotation velocity measuring unit for measuring rotation velocity of a wheel of the vehicle; characterized in that the apparatus comprises: a pressure sensor configured to detect a pressure in an interior of the tire of the vehicle; a wheel rotation velocity correcting unit configured to correct the measured rotation velocity of the wheel in accordance with detected pressure in the interior of the tire. a calculating unit configured to calculate changing amount of measured rotation velocity of the wheel by using the corrected rotation velocity of the wheel; an acceleration ratio calculating unit configured to calculate acceleration ratio S = (a w /a x) that is ratio between vehicle longitudinal acceleration a x measured by the vehicle longitudinal acceleration measuring unit and changing amount a w of the rotation velocity calculated by the calculating unit; and a wear amount estimating unit configured to estimate wear amount of the tire mounted on the vehicle from said calculated acceleration ratio S = (a w /a x). a vehicle longitudinal acceleration measuring unit installed to a vehicle body side of a vehicle and measuring longitudinal acceleration of the driven vehicle; and a wheel rotation velocity measuring unit for measuring rotation velocity of a wheel of the vehicle; characterized in that the apparatus comprises: a pressure sensor configured to detect a pressure in an interior of the tire of the vehicle; a wheel rotation velocity correcting unit configured to correct the measured rotation velocity of the wheel in accordance with detected pressure in the interior of the tire. a calculating unit configured to calculate changing amount of measured rotation velocity of the wheel by using the corrected rotation velocity of the wheel; an acceleration ratio calculating unit configured to calculate acceleration ratio S = (a w /a x) that is ratio between vehicle longitudinal acceleration a x measured by the vehicle longitudinal acceleration measuring unit and changing amount a w of the rotation velocity calculated by the calculating unit; and a wear amount estimating unit configured to estimate wear amount of the tire mounted on the vehicle from said calculated acceleration ratio S = (a w /a x). a pressure sensor configured to detect a pressure in an interior of the tire of the vehicle; a wheel rotation velocity correcting unit configured to correct the measured rotation velocity of the wheel in accordance with detected pressure in the interior of the tire. a calculating unit configured to calculate changing amount of measured rotation velocity of the wheel by using the corrected rotation velocity of the wheel; an acceleration ratio calculating unit configured to calculate acceleration ratio S = (a w /a x) that is ratio between vehicle longitudinal acceleration a x measured by the vehicle longitudinal acceleration measuring unit and changing amount a w of the rotation velocity calculated by the calculating unit; and a wear amount estimating unit configured to estimate wear amount of the tire mounted on the vehicle from said calculated acceleration ratio S = (a w /a x).