To highly accurately and inexpensively manufacture a thin-walled component with a complicated shape related to medical appliances and aircraft components by an injection molding method of titanium powder and titanium alloy.

A mass production by the injection molding is materialized by kneading a binder with the titanium powder so as to reduce the cost. This is attained by performing defatting and sintering processes of the binder in a vacuum sintering furnace as a single process (One-Step), and a device for forming a complicated shape by an insert (a placed core) and removing it by solvent. This manufacturing method combines the step and device together.