PURPOSE: To securely mount a can container on the position of center of rotation of a transfer means for a 2nd can container by providing a positioning member at the 2nd can container transfer means.

CONSTITUTION: A can container X is mounted by clamping a pawl piece 8, a 2nd locking part 18 of a positioning member 16 of a 2nd can container transfer means 2 transferring the can container X and a 1st locking part 17 of the positioning member 16 of the 2nd can container transfer means 2 accurately at the position of center of rotation of a supporting table 13. In this way, through the can container X is transferred at a high speed, the can container X is mounted securely and also from the 1st can container transfer means 1 on the position of center of rotation of the supporting table 13 through the 2nd can container transfer means 2, a can cover Y can be seamed at a high speed.