A container mounting structure includes a container, a container mounting portion, and a regulating section. The container has an opening, extends in one direction, and contains powder. When the container disposed at a predetermined temporarily placed position is rotated in a circumferential direction of the container, the container is mounted to the container mounting portion and the opening of the container is, with the container mounting portion, caused to be exposed. The regulating section regulates the rotation of the container in the circumferential direction in a case where the container is disposed at a position deviated from the temporarily placed position.