CYLINDRICAL MEMBER

To provide a cast iron cylindrical member capable of improving the bonding strength when metal on the outer peripheral side and the cast iron cylindrical member are integrated. For this objective, in a cast iron cylindrical member including a plurality of projections including constricted projections on the outer peripheral surface, the anchor portion index (I) represented by {(A2 - B2 ) × π/4 × Pn x Pr/100} × 0.35H/2 is set in a specific range.