An apparatus and method for measuring the speed of a moving object is provided. A first acceleration along the moving direction of the moving object and a second acceleration along the lateral direction of the moving object are measured. A first angular speed along the lateral direction of the moving object and a second angular speed along the lower direction of the moving object are measured. The roll angle of the moving object using the second acceleration, the second angular speed, and a previous speed of the moving object in the moving direction of the moving object, and a previous road inclination angle with respect to the moving direction of the moving object are calculated. A road inclination angle is calculated using the calculated roll angle, the first angular speed, and the second angular speed. A pure motion acceleration in the moving direction of the moving object is calculated using the calculated road inclination angle and the speed of the moving object is calculated using the pure motion acceleration of the moving object.