A manufacturing method of press-molded article of the present invention comprises a step of placing a member to be pressed in a press molding apparatus and a step of pressing a flat plate portion of the member to be pressed by bringing a first press portion and a second press portion closer to each other. A first opposing surface and a second opposing surface, while facing to each other, keep in contact with the flat plate portion during pressing. In the press step, a thick part is formed on the flat plate portion by allowing a part of a material of the flat plate portion to flow, in a press direction, into a thickened portion-forming section formed on the first opposing surface. The second opposing surface is moved to the press direction as the flat plate portion is pressed by the first press portion and the second press portion.