© in a method of preparing a sand mold in which mold sand within a mold frame (2) is squeezed from an upper side opposite to a lower side of the frame at which a pattern is embedded and also from said lower side, the squeezing from the lower side is made only after the squeezing from the upper side has been completed by about or more than 95% of a total squeezing stroke. The sand mold (3) thus prepared comes to have a desired hardness particularly at casting surfaces thereof.