A vehicle gradient estimating device includes: a vehicle speed sensor which detects a traveling speed of a subject vehicle; an acceleration calculating unit which calculates an acceleration of the subject vehicle on the basis of the traveling speed; an engine load deceleration calculating unit which calculates a deceleration due to an engine load of the subject vehicle; an acceleration correcting unit which corrects the acceleration by using the deceleration; a brake fluid pressure detecting unit which detects a brake fluid pressure of the subject vehicle; and a first gradient estimating unit which estimates a gradient of a road being traveled of the subject vehicle, wherein the first gradient estimating unit estimates the gradient on the basis of a ratio between the brake fluid pressure and the acceleration corrected by the acceleration correcting unit.