PURPOSE: To enable sufficient polishing of the side end part of the cylinder head of a flame coating film, by a method wherein the side end part is polished after a flame coating material is flame-coated on the inner wall of a cylinder in a state to apply masking on the interior of the cylinder head of a monoblock engine by means of a masking jig.

CONSTITUTION: A linear flame coating material 4 is flame-coated on an inner wall 2a of a cylinder by means of a discharge unit 7 in a state to insert a masking jig 5 in an inner wall 1a of a combustion chamber in a cylinder head 1 of a monoblock engine 3. Polishing processing is applied on a flame coating film 4a by means of a grinding stone. This method prevents a flame-coating film from being formed to a portion between a position right above a top ring, mounted to a piston at the top dead center of the piston, and a boundary between a cylinder head and a cylinder block, enables uniform polishing of the flame coating film, and enables prevention of damage of the flame coating film due to collision of the film with a piston during raising of the piston.