PURPOSE: To improve cooling performance of a bore surface by improving the heat transfer efficiency from a liner to a cylinder block main body, and to improve sealing performance between the liner and the cylinder block main body so as to improve the output performance of an engine.

CONSTITUTION: In a method for manufacturing a liner integrated cylinder block comprising a cylider block main body 1 made of an aluminum base alloy and a liner 2 mounted on the cylinder block main body 1 to form a bore, the cylinder block main body 1 and the liner 2 are welded by friction welding to be joined to each other. As the cylinder block main body 1 and the liner 2 are welded, and bonded together metallurgically at the atom-molecule level, thermal resistance between the liner 2 and the cylinder block main body 1 is small so as to be excellent in heat transfer efficiency from the liner 2 to the cylinder block main body 1.