To provide a calibration quality determination apparatus and its method for discriminating that calibration is normally completed in a calibration process of a measuring apparatus for highly accurately measuring a lateral velocity and a sideslip angle of a moving object.

A calibration quality determination apparatus 30 is configured so that a first antenna and a second antenna of GPS and a motion sensor 20 are arranged at predetermined distances, performs calibration, calculates an advancing direction at the start of the calibration, integrates a horizontal velocity out of velocities of a moving object in each direction, calculates a relative distance in each direction, converts the relative distance calculated in each direction into a distance of a coordinate system based on the direction of calibration start, and when a distance in the advancing direction out of the converted distances reaches a predetermined distance, determines whether or not a horizontal runout quantity indicated by a distance of a direction orthogonal to the advancing direction is equal to or less than a threshold, and informs success or fail of calibration.