A magnetic field measurement system for canceling an external field is provided, in which plurality of sensing magnetometers (3) for measuring a magnetic field signal in a direction perpendicular to the center axis of a cylindrical magnetic shield (1) are arranged in two dimensions on a plane parallel to the center axis and a reference magnetometer (4) for measuring the external field parallel to the center axis as a reference signal is disposed on a plane perpendicular to the plane parallel to the center axis. The reference signal multiplied by a specified factor is subtracted from a difference between signals from the adjacent sensing magnetometers (3). The magnetic field measurement system allows measurement of an extremely weak magnetic field by efficiently canceling the external field.