To prevent difference in level between an upper end face of open deck type cylinder block and an upper end face of a cylinder liner caused by temperature rise in operating an engine, without changing a cylinder liner form and metallic mold structure.

A manufacturing method for an open deck type cylinder block 1 comprises: a casting process casting the cylinder block 1 by the enveloped casting of the cylinder liner 2 with molten aluminum alloy; and a friction stirring and joining process integrating border lines of an upper end face 1a of the open deck type cylinder block 1 cast by the casting step and an upper end face 2a of the cylinder liner 2, by means of friction stirring and joining.