A sliding member for a thrust bearing, comprising: a back metal layer; and a sliding layer on the back metal layer, wherein the sliding member has a partially annular shape, wherein the sliding layer comprises synthetic resin and fibrous particles dispersed in the synthetic resin at a volume ratio of 10 to 35% of a volume of the sliding layer, and the fibrous particles having an average particle size of 5 to 25 μm, wherein the fibrous particles having a major axis length of not shorter than 20 μm are included at a volume ratio of not less than 10% in relation to a volume of total fibrous particles, when viewed in an axial cross-sectional structure parallel to a central axis of the sliding member and perpendicular to a sliding surface of the sliding layer, and wherein, when a sliding surface side area is defined as an area from the sliding surface toward an interface between the sliding surface and the back metal layer in the axial cross-sectional structure, the sliding surface side area having a thickness of 25% of a sliding layer thickness; an interface side area is defined as an area from the interface toward the sliding surface, the interface side area having a thickness of 25% of the sliding layer thickness; and an intermediate area is defined as an area between the sliding surface side area and the interface side area, (i) in the sliding surface side area, the fibrous particles having a major axis length of not shorter than 20 μm have a dispersion index of 1.1 to 6, (ii) in the intermediate area, the fibrous particles having a major axis length of not shorter than 20 μm have the dispersion index of 0.1 to less than 1, and (iii) in the interface side area, the fibrous particles having a major axis length of not shorter than 20 μm have the dispersion index of 1.1 to 6, where the dispersion index is defined as an average of ratios X1/Y1 of the fibrous particles, X1 being a length of a fibrous particle parallel to the sliding surface in the axial cross-sectional structure, and Y1 being a length of the fibrous particle perpendicular to the sliding surface in the circumferential cross-sectional structure. a back metal layer; and a sliding layer on the back metal layer, wherein the sliding member has a partially annular shape, wherein the sliding layer comprises synthetic resin and fibrous particles dispersed in the synthetic resin at a volume ratio of 10 to 35% of a volume of the sliding layer, and the fibrous particles having an average particle size of 5 to 25 μm, wherein the fibrous particles having a major axis length of not shorter than 20 μm are included at a volume ratio of not less than 10% in relation to a volume of total fibrous particles, when viewed in an axial cross-sectional structure parallel to a central axis of the sliding member and perpendicular to a sliding surface of the sliding layer, and wherein, when a sliding surface side area is defined as an area from the sliding surface toward an interface between the sliding surface and the back metal layer in the axial cross-sectional structure, the sliding surface side area having a thickness of 25% of a sliding layer thickness; an interface side area is defined as an area from the interface toward the sliding surface, the interface side area having a thickness of 25% of the sliding layer thickness; and an intermediate area is defined as an area between the sliding surface side area and the interface side area, (i) in the sliding surface side area, the fibrous particles having a major axis length of not shorter than 20 μm have a dispersion index of 1.1 to 6, (ii) in the intermediate area, the fibrous particles having a major axis length of not shorter than 20 μm have the dispersion index of 0.1 to less than 1, and (iii) in the interface side area, the fibrous particles having a major axis length of not shorter than 20 μm have the dispersion index of 1.1 to 6, (i) in the sliding surface side area, the fibrous particles having a major axis length of not shorter than 20 μm have a dispersion index of 1.1 to 6, (ii) in the intermediate area, the fibrous particles having a major axis length of not shorter than 20 μm have the dispersion index of 0.1 to less than 1, and (iii) in the interface side area, the fibrous particles having a major axis length of not shorter than 20 μm have the dispersion index of 1.1 to 6,