A root portion 7a of a sipe blade 7 that protrudes from a surface 12a of a plaster casting mold 12 is coated with a coating layer 10 of an easily collapsible refractory material. A string-shaped exhaust hole forming member 11 of a casting refractory material is attached to the sipe blade 7 so as to be in contact with the coating layer 10. Molten metal M is poured onto the surface 12a of the plaster casting mold 12 in this state so as to cast a mold with the shape of the surface 12a transferred thereon and with the root portion 7a of the sipe blade 7 cast therein. The coating layer 10 is thereafter removed to form a slit around the root portion 7a of the sipe blade 7. The exhaust hole forming member 11 is also removed to form an exhaust hole communicating with the outside of the piece. Therefore, the slit and the exhaust hole communicate with each other. In this way, a mold provided with an exhaust mechanism can be simply produced.