To provide a technology that can form different sorts of products without causing a shortage of strength of a mold.

The mold can form different sorts of products. The mold includes: an insert die formed with a cavity surface; an inside main die disposed on the back side of the insert die; and an outside main die having a penetration area for storing the inside main die therein. The mold is configured such that the insert die and the inside main die are exchangeable according to the sort of a product to be formed.