Structure of mouth plug portion, and package

A structure of a mouth plug portion comprising:

• a tubular nozzle whose top is provided with an opening;
• and
• a cap that is detachably fitted to an outer periphery and the top of the nozzle and closes the opening when being attached to the nozzle, wherein
• the nozzle includes:
• a first outer protrusion provided partially in a circumferential direction of an outer peripheral surface of the nozzle at a position away from the top in an axial direction and protruding outward in a radial direction, and
• a second outer protrusion provided at a position further than the first outer protrusion in the axial direction with respect to the top and protruding outward in the radial direction from the outer peripheral surface of the nozzle,
• the first outer protrusion includes:
• a locking surface that locks the cap such that the cap is prevented from being pulled out, and
• a first guide surface spirally extending between the locking surface and the top,
• the cap includes:
• a cap body configured to be attached to the nozzle so as to cover the first outer protrusion and the opening, and
• a tamper band connected to a base end side of the cap body and formed into an annular shape that laterally covers the second outer protrusion when the cap body is attached to the nozzle, part of the tamper band in the circumferential direction being provided with a weak portion configured to be broken by an external force received from the second outer protrusion when the cap body is rotated,
• the cap body includes:
• a first inner protrusion that protrudes inward in the radial direction from an inner peripheral surface thereof and is configured to be locked on the locking surface when the cap body is attached to the nozzle, and
• a second inner protrusion that protrudes inward in the radial direction from the inner peripheral surface and is provided so as to be movable along the first guide surface in a state where the first inner protrusion is not locked on the locking surface, and
• the outer peripheral surface of the nozzle is provided with a second guide surface along which the first inner protrusion and the second inner protrusion move in the axial direction during attachment/detachment of the cap.