For cylinder head of diesel engine and bed of machine tools which are made of sand casting, residual stress and deformation are serious problems. These defects are known to be due to the restraint by sand mold of heat shrinkage during casting. In previous studies, Motoyama et al. [1-4] conducted dynamic measurement of the aluminum alloy casting the resulting sand mold reaction force and the casting shrinkage, but studies in iron castings has not been performed so far. A continuous measuring device of sand mold reaction force and casting shrinkage of the green sand was newly developed. In this study, using the newly developed device, the authors conduct continuous measurement of the sand mold reaction force and casting shrinkage that occur in iron casting in green sand mold. The measured results provide valuable information to produce high quality casting.