A floating-bush bearing device (1D, 1E) for rotatably supporting a rotational shaft, comprising: a floating bush having a cylindrical shape and including a bearing hole into which the rotational shaft is to be inserted; and a bearing housing which rotatably houses the floating bush, wherein at least one of an inner peripheral surface of the floating bush, an outer peripheral surface of the floating bush, or an inner peripheral surface of the bearing housing includes, in a cross section in an axial direction thereof, a plurality of land portions (311, 321, 411) having a true arc shape which is a part of a true circular shape, and a plurality of recess portions (312, 322, 412) being disposed at a position recessed from the land portions (311, 321, 411), the recess portions (312, 322, 412) being configured such that a distance between the recess portions (312, 322, 412) and a virtual true circular line (31a, 32a, 41a) passing through the land portions (311, 321, 411) increases in a direction opposite from a rotational direction of the rotational shaft from end portions of the land portions (311, 321, 411) opposite from the rotational direction of the rotational shaft, the inner peripheral surface and the outer peripheral surface of the floating bush are formed so as to include each of the land portions and the recess portions in a cross section in the axial direction of the floating bush, characterized in that the land portions on the inner peripheral surface of the floating bush and the land portions on the outer peripheral surface of the floating bush bearing are formed in regions which overlap with each other in a circumferential direction, and wherein the recess portions on the inner peripheral surface of the floating bush and the recess portions on the outer peripheral surface of the floating bush are formed in regions which overlap with each other in the circumferential direction. a floating bush having a cylindrical shape and including a bearing hole into which the rotational shaft is to be inserted; and a bearing housing which rotatably houses the floating bush, wherein at least one of an inner peripheral surface of the floating bush, an outer peripheral surface of the floating bush, or an inner peripheral surface of the bearing housing includes, in a cross section in an axial direction thereof, a plurality of land portions (311, 321, 411) having a true arc shape which is a part of a true circular shape, and a plurality of recess portions (312, 322, 412) being disposed at a position recessed from the land portions (311, 321, 411), the recess portions (312, 322, 412) being configured such that a distance between the recess portions (312, 322, 412) and a virtual true circular line (31a, 32a, 41a) passing through the land portions (311, 321, 411) increases in a direction opposite from a rotational direction of the rotational shaft from end portions of the land portions (311, 321, 411) opposite from the rotational direction of the rotational shaft, the inner peripheral surface and the outer peripheral surface of the floating bush are formed so as to include each of the land portions and the recess portions in a cross section in the axial direction of the floating bush, characterized in that the land portions on the inner peripheral surface of the floating bush and the land portions on the outer peripheral surface of the floating bush bearing are formed in regions which overlap with each other in a circumferential direction, and wherein the recess portions on the inner peripheral surface of the floating bush and the recess portions on the outer peripheral surface of the floating bush are formed in regions which overlap with each other in the circumferential direction.