A tire parameter estimation device that is economical and can accurately estimate tire parameters while taking into consideration both states of a vehicle and states of a road environment. A &mgr; gradient detecting circuit detects a &mgr; gradient on the basis of a wheel speed detected by a wheel speed detecting circuit. A gradient value comparing circuit determines a &mgr; gradient section value &mgr;r, which is a mean value of the &mgr; gradients from the &mgr; gradient detecting circuit, and calculates a rate (=&mgr;r/&mgr;I) of the &mgr; gradient mean value &mgr;r with respect to a &mgr; gradient initial value &mgr;. A tire temperature estimating circuit stores a table representing the relation between the rate and a tire temperature, and estimates a tire temperature corresponding to the rate calculated by the gradient value comparing circuit as the present tire temperature.