A double container (1, 101, 301), comprising: an inner layer body (4, 120, 310) provided with an upper opening contiguous with a content container portion; an outer layer body accommodating the inner layer body and including a mouth portion provided with an aperture, through which aperture ambient air is introduced between the inner layer body and the outer layer body; and a dispensing cap provided with a content dispensing spout and fitted to the mouth portion of the outer layer body, wherein the double container further comprises: an inside plug provided with a dispensing passage and fitted to the upper opening, the dispensing passage placing the container portion in communication with the dispensing spout; and a check valve configured to open and close the dispensing passage, a vent region (32, 33) is provided inside the dispensing cap, and a throttle passage (35, T1, T2) is provided in a passage extending from an ambient air introducing hole through the vent region to the aperture, the ambient air introducing hole placing the vent region in communication with the outside, wherein the inside plug has the dispensing passage in a ceiling wall covering the upper opening, and includes an inner circumferential wall standing from an edge of the ceiling wall, the dispensing cap includes a cylindrical wall that is engaged with and held by the mouth portion and that forms a vent passage in communication with the aperture between the mouth portion and the inner circumferential wall of the inside plug, and the dispensing spout and the ambient air introducing hole are provided in a top wall connecting to the cylindrical wall, the check valve includes a partition wall that is provided between the dispensing spout and the ambient air introducing hole and that extends between the ceiling wall and the top wall so as to define, with the inner circumferential wall, an inner space connecting to the ambient air introducing hole, the inside plug has a connection passage connecting the inner space and the vent passage between an upper surface of the inner circumferential wall and a lower surface of the top wall, and the throttle passage is provided in at least one of the vent passage and the connection passage, characterised in that the throttle passage (35, T1, T2) is configured so that the need of another check valve is eliminated. an inner layer body (4, 120, 310) provided with an upper opening contiguous with a content container portion; an outer layer body accommodating the inner layer body and including a mouth portion provided with an aperture, through which aperture ambient air is introduced between the inner layer body and the outer layer body; and a dispensing cap provided with a content dispensing spout and fitted to the mouth portion of the outer layer body, wherein the double container further comprises: an inside plug provided with a dispensing passage and fitted to the upper opening, the dispensing passage placing the container portion in communication with the dispensing spout; and a check valve configured to open and close the dispensing passage, an inside plug provided with a dispensing passage and fitted to the upper opening, the dispensing passage placing the container portion in communication with the dispensing spout; and a check valve configured to open and close the dispensing passage, a vent region (32, 33) is provided inside the dispensing cap, and a throttle passage (35, T1, T2) is provided in a passage extending from an ambient air introducing hole through the vent region to the aperture, the ambient air introducing hole placing the vent region in communication with the outside, wherein the inside plug has the dispensing passage in a ceiling wall covering the upper opening, and includes an inner circumferential wall standing from an edge of the ceiling wall, the dispensing cap includes a cylindrical wall that is engaged with and held by the mouth portion and that forms a vent passage in communication with the aperture between the mouth portion and the inner circumferential wall of the inside plug, and the dispensing spout and the ambient air introducing hole are provided in a top wall connecting to the cylindrical wall, the check valve includes a partition wall that is provided between the dispensing spout and the ambient air introducing hole and that extends between the ceiling wall and the top wall so as to define, with the inner circumferential wall, an inner space connecting to the ambient air introducing hole, the inside plug has a connection passage connecting the inner space and the vent passage between an upper surface of the inner circumferential wall and a lower surface of the top wall, and the throttle passage is provided in at least one of the vent passage and the connection passage, characterised in that the throttle passage (35, T1, T2) is configured so that the need of another check valve is eliminated.