Cap comprising a cap body (10, 710, 410) that is fixed to a container and has a pour spout opening, through which content of the container is poured out, a lid member (20, 720, 420) that is attached to and detached from the cap body to open and close the pour spout opening, and an elastic member (30, 730, 430) that couples the lid member to the cap body, wherein: the elastic member, which has been elastically deformed, is restored during at least part of the movement of the lid member away from the cap body, thereby enabling the lid member to be held away from the cap body; the cap further comprising a coupling member (40, 740, 440) that couples the lid member to the cap body, the coupling member being connected to the cap body via a first hinge mechanism (41, 741, 441) and connected to the lid member via a second hinge mechanism (42, 742, 442) that has an axis parallel to an axis of the first hinge mechanism, characterized in that an elastic member end portion of the elastic member and a coupling member end portion of the coupling member, which are connected to the cap body, are each connected to a circumferential wall portion of the cap body, the elastic member end portion is connected at a position lower than the coupling member end portion in an axial direction of the cap body, the elastic member is elastically deformable into a straight belt shape and a curved shape, and with the lid member attached to the cap body, the elastic member is kept in a curved shape without being elastically deformed, and during a process of detaching and moving away the lid member from the cap body, the elastic member is elastically deformed to elongate, and the elastic deformation exceeds a predetermined limit so that the elastic member is restored to have a curved shape such that the lid member is held away from the cap body. the elastic member, which has been elastically deformed, is restored during at least part of the movement of the lid member away from the cap body, thereby enabling the lid member to be held away from the cap body; the cap further comprising a coupling member (40, 740, 440) that couples the lid member to the cap body, the coupling member being connected to the cap body via a first hinge mechanism (41, 741, 441) and connected to the lid member via a second hinge mechanism (42, 742, 442) that has an axis parallel to an axis of the first hinge mechanism, characterized in that an elastic member end portion of the elastic member and a coupling member end portion of the coupling member, which are connected to the cap body, are each connected to a circumferential wall portion of the cap body, the elastic member end portion is connected at a position lower than the coupling member end portion in an axial direction of the cap body, the elastic member is elastically deformable into a straight belt shape and a curved shape, and with the lid member attached to the cap body, the elastic member is kept in a curved shape without being elastically deformed, and during a process of detaching and moving away the lid member from the cap body, the elastic member is elastically deformed to elongate, and the elastic deformation exceeds a predetermined limit so that the elastic member is restored to have a curved shape such that the lid member is held away from the cap body.