PROBLEM TO BE SOLVED: To provide a new detection method capable of sorting out and removing a defective product formed of interconnected spherical capsules which may be produced during the production of seamless capsules, in a mechanical and highly accurate manner.SOLUTION: In the present invention, a large number of seamless capsules C are successively supplied to an air contact area AR, and a defective product Cn formed of interconnected spherical capsules which may be produced during the production of the capsules is separated from a good-quality product Cg and removed. In the air contact area AR, the seamless capsules C are individually allowed to fall. In addition, air is directed to each falling seamless capsule C in a direction intersecting the falling direction, and the good-quality product Cg and the defective product Cn formed of interconnected spherical capsules are sorted out from each other according to a difference in flying distance caused by the air. With regard to the flying distance, the defective product Cn formed of interconnected spherical capsules which is heavier than the good-quality product Cg is blown off farther away from the air contact area AR, so that both products are sorted out from each other according to the difference in the flying distance.
