A thrust sliding bearing for supporting a load applied in a thrust direction to a strut-type suspension to be supported, comprising: an upper case which receives the load; a lower case which is rotatably combined with the upper case and forms an annular space between the lower case and the upper case; and an annular center plate which is placed in the annular space and realizes rotation between the upper case and the lower case, characterised in that the center plate has: - an annular bearing surface being a convex-curved surface which faces radially inward, which extends radially outward as going in an axial direction away from the lower case, and whose shape in cross-section in the axial direction is a circular arc in which a radially inner end of the bearing surface is located axially closer to the lower case than a radially outer end of the bearing surface; and - a lower surface of a conical surface shape whose shape in cross-section in the axial direction is linear, wherein a radially inner end of the lower surface is located axially below a radially outer end of the lower surface, the upper case has an annular load transmission surface which slides on the bearing surface of the center plate, the load transmission surface being a concave curved surface which faces radially outward, and whose shape in cross-section in the axial direction is a circular arc in which a radially inner end of the load transmission surface is located axially below a radially outer end of the load transmission surface in the thrust direction such that the load transmission surface is funnel-shaped, the lower case has a mounting surface of a conical surface shape which comes in contact with the lower surface of the center plate to fix the center plate on the lower case and whose shape in cross-section in the axial direction is linear, wherein: the circular arc of the bearing surface in cross-section in the axial direction of the center plate and the circular arc of the load transmission surface in the axial direction of the upper case have radiuses differing from each other to contact each other by line contact, at a position where their tangent lines in cross-section coincide. an upper case which receives the load; a lower case which is rotatably combined with the upper case and forms an annular space between the lower case and the upper case; and an annular center plate which is placed in the annular space and realizes rotation between the upper case and the lower case, characterised in that the center plate has: - an annular bearing surface being a convex-curved surface which faces radially inward, which extends radially outward as going in an axial direction away from the lower case, and whose shape in cross-section in the axial direction is a circular arc in which a radially inner end of the bearing surface is located axially closer to the lower case than a radially outer end of the bearing surface; and - a lower surface of a conical surface shape whose shape in cross-section in the axial direction is linear, wherein a radially inner end of the lower surface is located axially below a radially outer end of the lower surface, - an annular bearing surface being a convex-curved surface which faces radially inward, which extends radially outward as going in an axial direction away from the lower case, and whose shape in cross-section in the axial direction is a circular arc in which a radially inner end of the bearing surface is located axially closer to the lower case than a radially outer end of the bearing surface; and - a lower surface of a conical surface shape whose shape in cross-section in the axial direction is linear, wherein a radially inner end of the lower surface is located axially below a radially outer end of the lower surface, the upper case has an annular load transmission surface which slides on the bearing surface of the center plate, the load transmission surface being a concave curved surface which faces radially outward, and whose shape in cross-section in the axial direction is a circular arc in which a radially inner end of the load transmission surface is located axially below a radially outer end of the load transmission surface in the thrust direction such that the load transmission surface is funnel-shaped, the lower case has a mounting surface of a conical surface shape which comes in contact with the lower surface of the center plate to fix the center plate on the lower case and whose shape in cross-section in the axial direction is linear, wherein: the circular arc of the bearing surface in cross-section in the axial direction of the center plate and the circular arc of the load transmission surface in the axial direction of the upper case have radiuses differing from each other to contact each other by line contact, at a position where their tangent lines in cross-section coincide.