To provide a separator 100 for a pot-like container for cutting a remainder material 220 from the container 210 when a semifinished product 200 of the container with the flange-like remainder material 220 extending from a circular opening is made during a manufacturing process of the pot-like container 210 with the opening 211, wherein the container 210 can be cut from the semifinished product by simple equipment and replacement of components can be reduced.

The separator 1 has a circular rotary blade 10 and a rotary mechanism 20 for revolving the blade 10 along a circumference approximately the same as the opening for rotatably supporting the blade 10. It further has an advancing/retreating mechanism for relatively advancing/retreating the mechanism 20 for a position where the rotary blade 10 revolves and can cut a rim 211 of the opening of the semifinished product 200. For example the rotary mechanism 20 may be mainly constituted of a rotary shaft 21 and a rotary arm 22 provided on the shaft 21 to support the rotary blade 10 at the tip of the arm 22.