Disclosed is an apparatus and a method for measuring the speed of a land vehicle using an accelerometer. The method includes the steps of storing measurement data provided from an accelerometer; analyzing the measurement data to determine whether the vehicle is stopped; calculating a road angle using the measurement data of the accelerometer when it is determined, upon analysis, that the vehicle is moving; determining the sign of the road angle when the road angle is greater than a threshold value; compensating for a gravitational acceleration component included in the measurement data of the accelerometer using the road angle; and calculating the speed of the vehicle based on the acceleration of the vehicle with the gravitational acceleration component compensated. It is possible to reduce the number of expensive gyroscopes needed for a vehicle speed measuring apparatus, thereby reducing the cost of the apparatus.