PURPOSE: A master frame of a mold for producing Styrofoam products is provided to rapidly heat a movable mold using the small amount of steam by reducing an indoor space of a movable master frame. CONSTITUTION: A master frame of a mold for producing Styrofoam products comprises movable master frames(1,3) and fixed master frames(2,4). Molds are installed between the movable and fixed mater frames. A Styrofoam material in the molds is heated by heating the molds. The Styrofoam material is molded into a Styrofoam product using a foaming agent. Multiple space reducing elements(15) are formed inside the movable master frames and reduce steam retention spaces to reduce the used amount of steam.
