The measurement apparatus includes a distortion correcting unit configured to generate a plurality of correction signals by correcting the plurality of signals using a distortion coefficient which is stored in the apparatus, a square-root of sum of squares arithmetic unit configured to calculate a square-root of sum of squares of the plurality of correction signals, a first normalizing unit configured to generate a plurality of first normalized signals by dividing each of the plurality of correction signals by the square-root of sum of squares, and a phase arithmetic unit configured to calculate the position of the object based on the plurality of first normalized signals.