To provide a method for manufacturing an engine block for restraining extension of time required for a manufacturing process, and properly adjusting lubricity on a cylinder inner circumference surface.

This method for manufacturing the engine block 10 includes a grinding process for grinding the inner circumference surface of a cylinder liner 12 by a grinding tool with water-soluble cutting oil, and an irradiation process for irradiating only at a portion with plasma, where a piston ring 14 provided at a piston 13 reciprocating along the inner circumstance surface slides among the inner circumference surface of the cylinder liner 12 after the grinding process completes.