To provide a cylinder block capable of suppressing increase in the weight, capable of securing rigidity of the cylinder block, and excellent in performance and durability.

Cylinder liners 14A and 14B made of ferrous metal are casted in cylinder bores 12A and 12B of a cylinder block body 11, bearing members 31A-31D having a body part 32 having a bearing surface 32a and a reinforcement part 34 integrally formed are casted in a bearing part of crank journal parts 25-28 integrally formed with the cylinder block body 11, and a fitting part 36 formed on a distal end of the reinforcement part 34 of the bearing members 31A-31D is fitted to the cylinder liners 14A and 14B so as to transmit the load. Deformation of the crank journal parts 25-28 is prevented, and supporting rigidity of a crankshaft 2 is secured, and partial deformation of the cylinder liners 14A and 14B can be avoided, and piston slap vibration can be suppressed, and engine friction can be reduced.