To provide a casting mold manufacturing apparatus using steam heating. The apparatus includes a forming die having a cavity, a resin-coated sand supply section for supplying a resin-coated sand into the cavity, a steam supply section for supplying steam into the cavity, and a steam discharge section for discharging the steam from the cavity. At least a portion of the forming die is composed of a porous material having pores with an average diameter smaller than an average particle diameter of the resin-coated sand. At least a portion of the steam is supplied into the cavity through the porous material. Since it is possible to uniformly supply the steam into the cavity, a homogeneous casting mold can be manufactured.