PURPOSE: To improve the efficiency of venting and to prolong the life of metallic molds by using a porous material for the venting part of the molds.

CONSTITUTION: A venting part 10 consisting of a porous material is provided in contact with the metallic mold part contacting cavities 5 which are the parts for molding products, more particularly the parts where gases are liable to accumulate, that is, in the part where molding material is packed finally on the side opposite to a gate 4. Stainless steel materials and ceramic materials of 10W20 micron hole sizes are used for the porous material. A better effect is obtained by providing a gas vent 9.