Provided is a paper tube that can be used in a flavor-suctioning tool. A paper tube (1) of a single layer of a thick paper is formed into a hollow cylinder shape by rolling a rectangular thick paper (2) into a cylindrical shape thereby forming an overlapped part (2wr) where two edges overlap, and by adhering the two edges to one another at the overlapped part (2wr). The thick paper (2) has a basis weight of 100 to 300 g/m2, a thickness of 150 to 500 µm, and a density of 0.5 g/cm3 or greater. The diameter of the cylinder is 5 mm to 8 mm. A plurality of grooves (3) that are parallel to an axis (CL) of the cylinder are disposed in the outer circumferential surface or the inner circumferential surface of the cylinder.