To propose a method for molding a container having a recess by using an O-PET sheet etc.

In the molding method, an oriented synthetic resin sheet softened by a heater is arranged on a female mold, a male mold in which its outside projection surface facing the inside recessed surface of the female mold has a projection surface shape of the same shape as the recessed surface shape of the female mold is press-fitted into the female mold, and the whole surface of the oriented synthetic resin sheet is pressed uniformly by the outside projection surface. The male mold is formed from an elastic member. The method may includes the process in which before the process for press-fitting the male mold into the female mold, the oriented synthetic resin sheet is arranged close to the inside recessed surface of the female mold in advance by a vacuum forming method. To a support member constituting part of the male mold, on the surface of the outside projection of the male mold, the elastic member is fitted to have a layer of a desired thickness. The oriented synthetic resin sheet is the O-PET sheet, and the elastic member includes silicone rubber or fluororubber.