PURPOSE: To detect a seal member of a different type by detecting the change of a light detection pattern in a scanning apparatus of a liquid filled container.

CONSTITUTION: A liquid filled container is sealed by a stopper 81 or a cup 84 being a seal member. A photoelectric scanning apparatus 1 consists of a photodetector 2 and a light emitter 3. The photodetector 2 and the light emitter 2 are arranged to a container revolving course 12 between an inlet position 20 and two treatment positions 24, 25. When the container is carried through the scanning apparatus 1, the scanning beam 14 from the transmitter is controlled in height level by the control unit 40 driven by a microcomputer. The shape and dimension of the seal member 8 are detected by low intensity 50 and the type of the seal member is grasped by high intensity 51. The container having the stopper 81 is sent to an opening means 26 and the container fitted with the cup 84 or not fitted therewith is moved to a liquid aspirator 27.