In a method for manufacturing a cylinder block provided with cylinder bores, the cylinder block is held by a clamp device, stress is generated in the cylinder block by a holding force of the clamp device to duplicate deformations of the cylinder bores after assembling hearing caps thereon, boring is carried out with the cylinder bores deformed in a condition where the stress is generated, and a thermally sprayed coating is formed, after the boring, on each inner surfaces of the cylinder bores deformed in the condition where the stress is generated. According to the method for manufacturing a cylinder block, superior cylindricity, after assembling the bearing caps, of the cylinder bores on each of which the thermally sprayed coating is formed can be brought, and workability degradation of finishing works (honing) for each inner surface of the cylinder bores (thermally sprayed coatings) can be restricted.