Provided are a medical container which shows a display visually recognizable only until a partition wall is separated on a partition wall section of opposed films on outer surfaces of the medical container to display an attention-drawing indicator until immediately before use and deletes the display instantly when the container is opened and brought into a state where partitioned parts communicate with each other, and a method of using the medical container. More particularly, provided is a container which is appropriately used as a multiple-chamber container having a plurality of chambers accommodating a plurality of medicines or the like to be mixed immediately before use, and which can provide a visual indication of whether the separable partition wall has been separated or not so that the condition of the respective chambers communicating with each other can be instantly checked when the multiple-chamber container is used.