To provide a mixing container which is simple in the structure and which can be easily operated and further through which an aseptic operation can be done.

This mixing container is provided with the first container 1 with a wide-mouthed opening 11, the second container 2 contained and held in the opening 11 of the first container 1, a packing 4 to seal water-tightly the gap between the second container 2 and the opening 11 of the first container 1, and a connecting means 3 fitted to the opening of the first container so as to slide downward. A through hole 22 is formed at the top face 21 of the second container 2 and a flange 24 is formed at the opened end face 23 of the bottom. The through hole 22 and the opened end face 24 are covered with films 6, 7 having a gas barrier property. When the connecting means 3 is slid downward, the films are opened by the connecting means 3.