A method for calibrating unevenness of a plurality of measuring elements in an apparatus for evaluating road surface property having a plurality of measuring elements repeats steps of computing separation quantities from a calibration reference plane on a reference area regarding all measuring elements; determining a measuring element where the separation quantity is maximum from among all the measuring element to calibrate the measuring element such that a difference between point cloud data produced from a measurement value of the measuring element where the separation quantity is maximum and the calibration reference plane becomes equal or less than a predetermined value, producing a new calibration reference plane from the measurement values of the measuring elements including the calibrated measuring element, until RMS of point cloud data does not change.