To provide a sand mold for improving the machining precision of a cast V block.

An engine block mold package is assembled from a resin-bonded sand mold cores in a manner which reduces parting line on the exterior surfaces of the mold package. An assembly of multiple cores (core packages) is formed and provided with multiple inter-core parting lines extending in different directions in the exterior surface of the core assembly. The core package is disposed between a base core and a cover core. This cover core is constituted so as to form a single continuous exterior parting line around the assembled mold package by enclosing the core package.