To obtain a bering structure of a head pipe for a folding bicycle capable of ensuring a wide interval between both bearings respectively arranged at both end portions of the head pipe, even if the head pipe is made to be short.
In the bearing structure 10, an adjusting member 32 for adjusting an axial pressing load of an upper ball bearing 12 and a lower ball bearing 14 by changing screwing amount, and a plug-shaped screw 42 (a fixing member) with a projecting hexagonal rod for pressing the adjusting member 32 in an axial direction to fix are disposed in a cylinder of the head pipe 62. The upper ball bearing 12 and the lower ball bearing 14 are disposed in the outermost side at both end portions of the head pipe 62. Therefore, even if axial dimensions of the head pipe 62 are made to be shorter than interval measurements H between the upper ball bearing 12 and the lower ball bearing 14 at both end portions of the head pipe 62 can be ensured to be long. No excessive protrusion exists on an upper side of the head pipe 62, so that folding hinge 70 can be arranged just above the upper ball bearing 12, and the volume of the folding bicycle in a folded state can be miniaturized.