To provide a filling system of a cup-shaped container 2 which easily replaces different size containers 2A and 2B.

A container holding means 26 which is attached to a chain 24 at a specified interval has a first support plate 26A formed with a support hole 26Aa of a small diameter, and a second support plate 26B formed with a support hole 26Ba larger than the support hole 26Aa. The second support plate 26B is vertically movable with respect to the first support plate 26A, and when vertical movement is performed, positions of both of the support holes 26Aa and 26Ba are fixed by a positioning pin 34. If the small-size container 2A is conveyed, the second support plate 26B is descended and placed on the first support plate 26A, and then inserted into both of the support holes 26Aa and 26Ba. On the other hand, if the container 2B of a large size is conveyed, the second support plate 26B is ascended, and then the container 2B of a cup shape is inserted into the support hole 26Ba.