To provide a mold wash material for a sand mold, which imparts burning resistance with seizure resistance to a sand mold, effectively suppresses gas defect on a casting surface layer part and is excellent in workability.

There is provided a chromite coating used as a mold wash material, an undercoating coating material applied to the sand mold, in which chromite is used as an aggregate formed by mixing a first particle group at a small diameter side and a second particle group at a large diameter side and which includes a first peak at the small diameter side and a second peak at the large diameter side as a maximum value peak of particle size distribution.