A method of molding a plastic is initiated by inject­ing molten resin into a mold at a high pressure. The energy of the high pressure is partially stored in the form of elongation of tie bars of a molding machine. After the gate seals completely, the restoring force of the tie bars due to elastic deformation acts on the molded article as the molded article cools down. Each tie bar comprises a first member having a small modulus of elastic­ity and a second member. When the elongation of each tie bar is small, only the first member of small modulus of elasticity works. After the elongation reaches a certain amount of Δℓ₁, the two members are connected parallel. As a result, the apparent modulus of elasticity of each tie bar increases rapidly. This makes it possible to mold a plastic with high dimensional accuracy.