A container comprising: a container body containing contents and having a container inlet; and a container cap combined with the container inlet, wherein a plurality of close contact portions in close contact with each other are formed on the container cap and the container inlet, and the close contact portions form a closed curve enclosing the container inlet so as to block inflow of external air from the outside into the container body; wherein the container cap comprises: a body part in close contact with an upper end of the container inlet; a sidewall part which extends downward from the body part and in which a female screw part that is screw-coupled with a male screw part formed on an outer circumferential surface of the container inlet is formed; and an inner ring protruding from a bottom surface of the body part and inserted to an inner circumferential surface of the container inlet;and wherein a middle ring inserted to a recessed groove having a circular shape formed on the upper end of the container inlet and formed on the bottom surface of the body part to form at least one close contact portion when the container cap is combined with the container inlet is formed on the container cap; characterized in that: at least one of an inner upper end and an outer upper end of the container inlet has a curved outer circumferential surface, and an inclined surface in contact with the curved outer circumferential surface when the container cap is combined with the container inlet is formed on the container cap. a container body containing contents and having a container inlet; and a container cap combined with the container inlet, wherein a plurality of close contact portions in close contact with each other are formed on the container cap and the container inlet, and the close contact portions form a closed curve enclosing the container inlet so as to block inflow of external air from the outside into the container body; wherein the container cap comprises: a body part in close contact with an upper end of the container inlet; a sidewall part which extends downward from the body part and in which a female screw part that is screw-coupled with a male screw part formed on an outer circumferential surface of the container inlet is formed; and an inner ring protruding from a bottom surface of the body part and inserted to an inner circumferential surface of the container inlet;and wherein a middle ring inserted to a recessed groove having a circular shape formed on the upper end of the container inlet and formed on the bottom surface of the body part to form at least one close contact portion when the container cap is combined with the container inlet is formed on the container cap; characterized in that: at least one of an inner upper end and an outer upper end of the container inlet has a curved outer circumferential surface, and an inclined surface in contact with the curved outer circumferential surface when the container cap is combined with the container inlet is formed on the container cap. a body part in close contact with an upper end of the container inlet; a sidewall part which extends downward from the body part and in which a female screw part that is screw-coupled with a male screw part formed on an outer circumferential surface of the container inlet is formed; and an inner ring protruding from a bottom surface of the body part and inserted to an inner circumferential surface of the container inlet;and wherein a middle ring inserted to a recessed groove having a circular shape formed on the upper end of the container inlet and formed on the bottom surface of the body part to form at least one close contact portion when the container cap is combined with the container inlet is formed on the container cap; characterized in that: at least one of an inner upper end and an outer upper end of the container inlet has a curved outer circumferential surface, and an inclined surface in contact with the curved outer circumferential surface when the container cap is combined with the container inlet is formed on the container cap. at least one of an inner upper end and an outer upper end of the container inlet has a curved outer circumferential surface, and an inclined surface in contact with the curved outer circumferential surface when the container cap is combined with the container inlet is formed on the container cap.