An imaging system that calibrates parameters of imaging apparatuses (10, 10A to 10N, 10Aa to 10Na) disposed in different positions, the imaging system comprising: a movable object that includes a marker for use in calibration for the imaging apparatuses (10, 10A to 10N, 10Aa to 10Na), moved in an imaging area (A1) in a three-dimensional space, the imaging area (A1) being a common imaging area for the imaging apparatuses (10, 10A to 10N, 10Aa to 10Na); characterized in that , the imaging system further comprises: a control apparatus comprising a controller including: an imaging controller that causes the imaging apparatuses (10, 10A to 10N, 10Aa to 10Na) to image (S42) the marker ; a movement controller that causes the moveable object to move (S36A, S41, S46); and, a calibrator that calibrates (S36B, S45, S63, S75) external parameters of the imaging apparatuses (10, 10A to 10N, 10Aa to 10Na), using images captured by each of the imaging apparatuses (10, 10A to 10N, 10Aa to 10Na) imaging the marker in each of three-dimensional positions different from one another, said images being arranged as input to the calibrator for use in calibration processing (S36B) to produce said external parameters of the imaging apparatuses, for output (S37), wherein the calibrator calibrates the external parameters of the imaging apparatuses (10, 10A to 10N, 10Aa to 10Na) by associating, for each of the three-dimensional positions, the markers included in, among the images, two or more images captured when the marker is in the three-dimensional position, as common feature points in the two or more images, and the movement controller causes (S46) the moveable object to move from a first area (All to A14, A21, A22, A24) in the imaging area (A1) to a second area (A23) that includes, among the common feature points, a lower number of associated features points than the first area (All to A14, A21, A22, A24). an imaging controller that causes the imaging apparatuses (10, 10A to 10N, 10Aa to 10Na) to image (S42) the marker ; a movement controller that causes the moveable object to move (S36A, S41, S46); and, a calibrator that calibrates (S36B, S45, S63, S75) external parameters of the imaging apparatuses (10, 10A to 10N, 10Aa to 10Na), using images captured by each of the imaging apparatuses (10, 10A to 10N, 10Aa to 10Na) imaging the marker in each of three-dimensional positions different from one another, said images being arranged as input to the calibrator for use in calibration processing (S36B) to produce said external parameters of the imaging apparatuses, for output (S37), wherein the calibrator calibrates the external parameters of the imaging apparatuses (10, 10A to 10N, 10Aa to 10Na) by associating, for each of the three-dimensional positions, the markers included in, among the images, two or more images captured when the marker is in the three-dimensional position, as common feature points in the two or more images, and the movement controller causes (S46) the moveable object to move from a first area (All to A14, A21, A22, A24) in the imaging area (A1) to a second area (A23) that includes, among the common feature points, a lower number of associated features points than the first area (All to A14, A21, A22, A24). <EOS>