A fluid dispersing device comprising: a tubular first wall portion with an inlet and an outlet and an inner space through which fluid is capable of passing from the inlet to the outlet, and with an axis extending in a first direction defined as a central axis; and a second wall portion separated from the first wall portion on a downstream side in the first direction, wherein the first wall portion is positioned on an upstream side in the first direction, wherein the second wall portion has a conical shape entirely tapered on the downstream side, the second wall portion including at least one annular circular member (3a, 3b, 3c, 3d, 3e) and a disk-like member each having a flat surface for causing a fluid passing through the inner space of the first wall portion to collide therewith, the flat surface being perpendicular to the axis, the disk-like member being separated from the at least one annular circular member (3a, 3b, 3c, 3d, 3e) on the downstream side in the first direction, wherein the disk-like member is configured such that the fluid passing through the first wall portion does not flow straight or directly out of the second wall portion, support portions each having a stick shape, and supporting the at least one annular circular member (3a, 3b, 3c, 3d, 3e) such that one end is fixed to the first wall portion, and at least one portion is fixed to the outer circumferences of the at least one annular circular member (3a, 3b, 3c, 3d, 3e), wherein: the at least one annular circular member (3a, 3b, 3c, 3d, 3e) includes a first annular circular member closest to the first wall portion and a second annular circular member separated from the first annular circular member on the downstream side in the first direction; the first annular circular member has a first outer diameter and a first inner diameter; the second annular circular member has a second outer diameter and a second inner diameter; the first outer diameter is equal to or smaller than the inner diameter of the first wall portion; the second outer diameter is smaller than the first outer diameter; the second inner diameter is equal to or smaller than the first inner diameter; and a diameter of the disk-like member is equal to or smaller than an outer diameter of the closest annular circular member. a tubular first wall portion with an inlet and an outlet and an inner space through which fluid is capable of passing from the inlet to the outlet, and with an axis extending in a first direction defined as a central axis; and a second wall portion separated from the first wall portion on a downstream side in the first direction, wherein the first wall portion is positioned on an upstream side in the first direction, wherein the second wall portion has a conical shape entirely tapered on the downstream side, the second wall portion including at least one annular circular member (3a, 3b, 3c, 3d, 3e) and a disk-like member each having a flat surface for causing a fluid passing through the inner space of the first wall portion to collide therewith, the flat surface being perpendicular to the axis, the disk-like member being separated from the at least one annular circular member (3a, 3b, 3c, 3d, 3e) on the downstream side in the first direction, wherein the disk-like member is configured such that the fluid passing through the first wall portion does not flow straight or directly out of the second wall portion, support portions each having a stick shape, and supporting the at least one annular circular member (3a, 3b, 3c, 3d, 3e) such that one end is fixed to the first wall portion, and at least one portion is fixed to the outer circumferences of the at least one annular circular member (3a, 3b, 3c, 3d, 3e), wherein: the at least one annular circular member (3a, 3b, 3c, 3d, 3e) includes a first annular circular member closest to the first wall portion and a second annular circular member separated from the first annular circular member on the downstream side in the first direction; the first annular circular member has a first outer diameter and a first inner diameter; the second annular circular member has a second outer diameter and a second inner diameter; the first outer diameter is equal to or smaller than the inner diameter of the first wall portion; the second outer diameter is smaller than the first outer diameter; the second inner diameter is equal to or smaller than the first inner diameter; and a diameter of the disk-like member is equal to or smaller than an outer diameter of the closest annular circular member. the at least one annular circular member (3a, 3b, 3c, 3d, 3e) includes a first annular circular member closest to the first wall portion and a second annular circular member separated from the first annular circular member on the downstream side in the first direction; the first annular circular member has a first outer diameter and a first inner diameter; the second annular circular member has a second outer diameter and a second inner diameter; the first outer diameter is equal to or smaller than the inner diameter of the first wall portion; the second outer diameter is smaller than the first outer diameter; the second inner diameter is equal to or smaller than the first inner diameter; and a diameter of the disk-like member is equal to or smaller than an outer diameter of the closest annular circular member.