A method for manufacturing an internal combustion engine, wherein the internal combustion engine comprises: a cylinder body comprising a cylinder, a water jacket formed around the cylinder, a first hole that is formed outward of the water jacket in a radial direction of the cylinder and that extends parallel to an axial line of the cylinder; a cylinder head that comprises a hole extending on a center line of the first hole and that covers the cylinder; and a first bolt that is inserted into the first hole and the hole of the cylinder head to fasten together the cylinder head and the cylinder body, wherein: as the cylinder body is seen along the axial line of the cylinder, the cylinder body comprises an outer contour that defines an outer side of the water jacket in the radial direction of the cylinder, an inner contour that defines an inner side of the water jacket in the radial direction of the cylinder, a first opposing surface that is located outward of the outer contour in the radial direction of the cylinder and that opposes the cylinder head, and a second opposing surface that is located inward of the inner contour in the radial direction of the cylinder and that opposes the cylinder head; and as the cylinder body is seen along the axial line of the cylinder, the outer contour comprises a first depressed portion that is located radially outward of the first hole and that is depressed in a direction radially outward of the cylinder, the method comprising: preparing a mold comprising a water jacket molding portion that has the same shape as the water jacket and that comprises a cooling passage formed therein; injecting a metal material into the mold; and supplying a coolant to flow through the cooling passage, thereby cooling the mold. a cylinder body comprising a cylinder, a water jacket formed around the cylinder, a first hole that is formed outward of the water jacket in a radial direction of the cylinder and that extends parallel to an axial line of the cylinder; a cylinder head that comprises a hole extending on a center line of the first hole and that covers the cylinder; and a first bolt that is inserted into the first hole and the hole of the cylinder head to fasten together the cylinder head and the cylinder body, wherein: as the cylinder body is seen along the axial line of the cylinder, the cylinder body comprises an outer contour that defines an outer side of the water jacket in the radial direction of the cylinder, an inner contour that defines an inner side of the water jacket in the radial direction of the cylinder, a first opposing surface that is located outward of the outer contour in the radial direction of the cylinder and that opposes the cylinder head, and a second opposing surface that is located inward of the inner contour in the radial direction of the cylinder and that opposes the cylinder head; and as the cylinder body is seen along the axial line of the cylinder, the outer contour comprises a first depressed portion that is located radially outward of the first hole and that is depressed in a direction radially outward of the cylinder, the method comprising: preparing a mold comprising a water jacket molding portion that has the same shape as the water jacket and that comprises a cooling passage formed therein; injecting a metal material into the mold; and supplying a coolant to flow through the cooling passage, thereby cooling the mold. as the cylinder body is seen along the axial line of the cylinder, the cylinder body comprises an outer contour that defines an outer side of the water jacket in the radial direction of the cylinder, an inner contour that defines an inner side of the water jacket in the radial direction of the cylinder, a first opposing surface that is located outward of the outer contour in the radial direction of the cylinder and that opposes the cylinder head, and a second opposing surface that is located inward of the inner contour in the radial direction of the cylinder and that opposes the cylinder head; and as the cylinder body is seen along the axial line of the cylinder, the outer contour comprises a first depressed portion that is located radially outward of the first hole and that is depressed in a direction radially outward of the cylinder, the method comprising: preparing a mold comprising a water jacket molding portion that has the same shape as the water jacket and that comprises a cooling passage formed therein; injecting a metal material into the mold; and supplying a coolant to flow through the cooling passage, thereby cooling the mold. preparing a mold comprising a water jacket molding portion that has the same shape as the water jacket and that comprises a cooling passage formed therein; injecting a metal material into the mold; and supplying a coolant to flow through the cooling passage, thereby cooling the mold.