A method of manufacturing a product having a sprayed coating film prepares a component having a cylindrical inner surface, prepares a gas spray type spraying gun with a central axis in opposed relationship with the cylindrical inner surface of the component to be aligned with a central axis of the cylindrical inner surface, supplies spraying material to the spraying gun, melts the spraying material with a combustion flame, and travels the spraying gun for translational movement in a traveling direction, corresponding to one of directions of the central axis of the cylindrical inner surface, for forming a sprayed coating film over the cylindrical inner surface while spraying the spraying material, molten with the combustion flame, onto the cylindrical inner surface in a spraying direction oriented in a rearward area of the traveling direction for thereby forming the sprayed coating film over the cylindrical inner surface.