A cast-iron cylindrical member having an outer peripheral surface, the outer peripheral surface of the cast-iron cylindrical member being made up of a casted surface and having a plurality of projections formed integrally with the casted surface, wherein: the plurality of projections have an average height equal to or larger than 0.20 mm and smaller than 0.50 mm; a total number of the plurality of projections per cm 2 of the outer peripheral surface is equal to or larger than 61 and equal to or smaller than 180; the plurality of projections comprise a projection (Pn) having a constricted shape; a ratio of a number of the projections (Pn) having the constricted shape to a number of the plurality of projections present on the outer peripheral surface is equal to or larger than 50%; a value S expressed by: S = H 2 × N × NP is equal to or larger than 310; and any one condition selected from a group consisting of: a bonding strength F (Al) obtained when the outer peripheral surface of the cast-iron cylindrical member is cast-in inserted with an aluminum alloy exceeds a value Fb expressed by: Fb = 1.325 × H 2 × N − 0.75; and a ratio of the number of projections (Pn) having the constricted shape, each having 0.65 or smaller as a ratio of a height of a position of a most constricted portion to a height of the projection (Pn) having the constricted shape, to the number of projections (Pn) having the constricted shape present on the outer peripheral surface is equal to or larger than 40%, is satisfied, in Expression and Expression, S is a bonding strength index, H is the average height in mm of the plurality of projections, N is a total number in number/cm 2 of the plurality of projections per cm 2 of the outer peripheral surface, NP is a ratio (%) of the number of projections (Pn) having the constricted shape to the number of the plurality of projections present on the outer peripheral surface, and Fb is a boundary bonding strength (MPa). the plurality of projections have an average height equal to or larger than 0.20 mm and smaller than 0.50 mm; a total number of the plurality of projections per cm 2 of the outer peripheral surface is equal to or larger than 61 and equal to or smaller than 180; the plurality of projections comprise a projection (Pn) having a constricted shape; a ratio of a number of the projections (Pn) having the constricted shape to a number of the plurality of projections present on the outer peripheral surface is equal to or larger than 50%; a value S expressed by: S = H 2 × N × NP is equal to or larger than 310; and any one condition selected from a group consisting of: a bonding strength F (Al) obtained when the outer peripheral surface of the cast-iron cylindrical member is cast-in inserted with an aluminum alloy exceeds a value Fb expressed by: Fb = 1.325 × H 2 × N − 0.75; and a ratio of the number of projections (Pn) having the constricted shape, each having 0.65 or smaller as a ratio of a height of a position of a most constricted portion to a height of the projection (Pn) having the constricted shape, to the number of projections (Pn) having the constricted shape present on the outer peripheral surface is equal to or larger than 40%, is satisfied, in Expression and Expression, S is a bonding strength index, H is the average height in mm of the plurality of projections, N is a total number in number/cm 2 of the plurality of projections per cm 2 of the outer peripheral surface, NP is a ratio (%) of the number of projections (Pn) having the constricted shape to the number of the plurality of projections present on the outer peripheral surface, and Fb is a boundary bonding strength (MPa). a bonding strength F (Al) obtained when the outer peripheral surface of the cast-iron cylindrical member is cast-in inserted with an aluminum alloy exceeds a value Fb expressed by: Fb = 1.325 × H 2 × N − 0.75; and a ratio of the number of projections (Pn) having the constricted shape, each having 0.65 or smaller as a ratio of a height of a position of a most constricted portion to a height of the projection (Pn) having the constricted shape, to the number of projections (Pn) having the constricted shape present on the outer peripheral surface is equal to or larger than 40%, is satisfied, in Expression and Expression, S is a bonding strength index, H is the average height in mm of the plurality of projections, N is a total number in number/cm 2 of the plurality of projections per cm 2 of the outer peripheral surface, NP is a ratio (%) of the number of projections (Pn) having the constricted shape to the number of the plurality of projections present on the outer peripheral surface, and Fb is a boundary bonding strength (MPa).