A paper container comprising: a bottom section; a body section provided to stand along from the bottom section; a right flap and a left flap formed in such a manner that the right and left flaps (11, 12) are folded inward along creases from the upside of the body section; a collar section formed in such a manner that the collar section is folded outward along a crease from the upside of the body section at one end side of the right and left flaps (11,12); and an insertion flap formed in such a manner that the insertion flap is folded inward along a crease from the upside of the body section at the other end side of the right and left flaps (11, 12); wherein the right flap and the left flap overlap each other to cover an opening formed by the body section; wherein the right flap and the left flap each has a slit on the insertion flap side; wherein the insertion flap is inserted into the slit to maintain the overlapping state of the right and left flaps (11, 12); and wherein there are collaterally provided between the body section and each one of the right and left flaps (11, 12) a first arc-shaped crease provided on the flap side, and a second arc-shaped crease provided on the body section side; wherein the collar section is provided with a first crease corresponding to the first arc-shaped crease, and a second crease corresponding to the second arc-shaped crease; wherein a wide tap can be formed by folding along the first arc-shaped crease and the first crease, and a narrow tap can be formed by folding along the second arc-shaped crease and the second crease. a bottom section; a body section provided to stand along from the bottom section; a right flap and a left flap formed in such a manner that the right and left flaps (11, 12) are folded inward along creases from the upside of the body section; a collar section formed in such a manner that the collar section is folded outward along a crease from the upside of the body section at one end side of the right and left flaps (11,12); and an insertion flap formed in such a manner that the insertion flap is folded inward along a crease from the upside of the body section at the other end side of the right and left flaps (11, 12); wherein the right flap and the left flap overlap each other to cover an opening formed by the body section; wherein the right flap and the left flap each has a slit on the insertion flap side; wherein the insertion flap is inserted into the slit to maintain the overlapping state of the right and left flaps (11, 12); and wherein there are collaterally provided between the body section and each one of the right and left flaps (11, 12) a first arc-shaped crease provided on the flap side, and a second arc-shaped crease provided on the body section side; a first arc-shaped crease provided on the flap side, and a second arc-shaped crease provided on the body section side; wherein the collar section is provided with a first crease corresponding to the first arc-shaped crease, and a second crease corresponding to the second arc-shaped crease; a first crease corresponding to the first arc-shaped crease, and a second crease corresponding to the second arc-shaped crease; wherein a wide tap can be formed by folding along the first arc-shaped crease and the first crease, and a narrow tap can be formed by folding along the second arc-shaped a wide tap can be formed by folding along the first arc-shaped crease and the first crease, and a narrow tap can be formed by folding along the second arc-shaped crease and the second crease.