MOLD FOR FORMING WATER JACKET

PROBLEM TO BE SOLVED: To provide a mold for forming a water jacket, in which a cooling mechanism capable of cooling the whole mold uniformly from the inside of the mold is provided while reducing the degradation of stiffness as much as possible.SOLUTION: The mold 10 for forming the water jacket comprising a cylinder block is configured by connecting a plurality of cylindrical portions 11. The mold further includes a cooling circuit 20, wherein the cooling circuit includes a plurality of peripheral flow paths 23 formed in multiple steps, the flow paths being formed inside of a peripheral wall 12 of the cylindrical portions 11 along the peripheral direction of the mold and being arranged apart from one another in an axial direction of the cylinder.