PURPOSE: To eliminate the space to allow entry of the outside air, by providing a cylindrical container with a vertically movable lower part to always keep the inner volume thereof equivalent to the volume required by the contents.

CONSTITUTION: A container 1 is provided with bottom 2 and top in the same cylindrical shape. The top opening of the container and its cap are threadedly engageable following the conventional sealing method and the inner volume of this container can be changed by moving the bottom 2 up and down. The lower part 2 may be of various shapes such as circle, square and ellipse. A short cylindrical leg 4 conforming with the inside diameter of the container is provided to maintain the bottom 2 in a horizontal position for facilitating its up and down motion. Not only when the container is full of contents but also when the contents are decreased, the inner volume of the container equivalent to the volume of the contents can be always obtained by moving up the bottom 2, whereby the space to allow entry of the outside air can be eliminated upon each opening or closing the container.