The present invention, it is possible to reduce the amount of wasted material molding, and when forming a plurality of molded products using a mold at the same time does not mold is larger in the plane, and thus provides a manufacturing efficiency is good method for forming a liquid elastomer. In order to achieve the above object, there is provided a method of using a mold forming a molded article made of a liquid elastomer, the mold (1) is a mold for injection molding, a plurality of the product cavity 51, the clamping and die opening of the die They are formed side by side in a direction, and, at the same time forming a plurality of molded products using a mold. The mold is provided, and the runner has, extending from the sprue to the direction perpendicular to the fastening type of the mold and die opening direction, a plurality of product cavity sprue 21, a runner 31 and a gate 41 leading to the the outer periphery of the installed perpendicular to the runner portion 32 and, perpendicular to and from the runner portion provided with the extension is installed parallel to the runner section 33 in a direction parallel to the clamping and die opening direction of the mold, parallel to the runner section, a plurality of product cavity It is disposed on one side.