A combination of a container and a synthetic resin container closure, in which: the container has a cylindrical mouth-and-neck portion; and an external thread and a locking jaw portion located below the external thread are formed on an outer peripheral surface of the mouth-and-neck portion, and the synthetic resin container closure is mounted on the mouth-and-neck portion of the container, and includes a circular top panel wall and a cylindrical skirt wall extending downwardly from a peripheral edge of the top panel wall; wherein a circumferential breakable line extending in a circumferential direction is formed in the skirt wall; wherein the skirt wall is divided into a main section above the circumferential breakable line and a tamper evident bottom section below the circumferential breakable line; wherein an internal thread to cooperate with the external thread of the mouth-and-neck portion is formed on an inner peripheral surface of the main section; and wherein locking means to cooperate with the locking jaw portion of the mouth-and-neck portion is disposed on an inner peripheral surface of the tamper evident bottom section, wherein an inverted truncated cone-shaped fitting surface, which extends upwards at a radially outward incline from a base edge of an upper surface of the locking means, is disposed in the inner peripheral surface of the tamper evident bottom section of the synthetic resin container closure, wherein, with the internal thread of the synthetic resin container closure being screwed onto the external thread of the mouth-and-neck portion to mount the synthetic resin container closure on the mouth-and-neck portion, thereby sealing the mouth-and-neck portion, an upper end edge of the fitting surface formed in the inner peripheral surface of the tamper evident bottom section is located to oppose an outer peripheral surface of the locking jaw portion of the mouth-and-neck portion, characterised in that an axial clearance C between the external thread and the internal thread is equal to or larger than an axial effective width W of the locking jaw portion (C ≥ W), and wherein the axial clearance C is larger than the axial effective width W by 0.0 to 0.7 mm (C - W = 0.0 to 0.7 mm). the container has a cylindrical mouth-and-neck portion; and an external thread and a locking jaw portion located below the external thread are formed on an outer peripheral surface of the mouth-and-neck portion, and the synthetic resin container closure is mounted on the mouth-and-neck portion of the container, and includes a circular top panel wall and a cylindrical skirt wall extending downwardly from a peripheral edge of the top panel wall; wherein a circumferential breakable line extending in a circumferential direction is formed in the skirt wall; wherein the skirt wall is divided into a main section above the circumferential breakable line and a tamper evident bottom section below the circumferential breakable line; wherein an internal thread to cooperate with the external thread of the mouth-and-neck portion is formed on an inner peripheral surface of the main section; and wherein locking means to cooperate with the locking jaw portion of the mouth-and-neck portion is disposed on an inner peripheral surface of the tamper evident bottom section, wherein an inverted truncated cone-shaped fitting surface, which extends upwards at a radially outward incline from a base edge of an upper surface of the locking means, is disposed in the inner peripheral surface of the tamper evident bottom section of the synthetic resin container closure, wherein, with the internal thread of the synthetic resin container closure being screwed onto the external thread of the mouth-and-neck portion to mount the synthetic resin container closure on the mouth-and-neck portion, thereby sealing the mouth-and-neck portion, an upper end edge of the fitting surface formed in the inner peripheral surface of the tamper evident bottom section is located to oppose an outer peripheral surface of the locking jaw portion of the mouth-and-neck portion, characterised in that an axial clearance C between the external thread and the internal thread is equal to or larger than an axial effective width W of the locking jaw portion (C ≥ W), and wherein the axial clearance C is larger than the axial effective width W by 0.0 to 0.7 mm (C - W = 0.0 to 0.7 mm).