A vapor deposition apparatus and method for efficiently performing a deposition process to form a thin film with improved characteristics on a substrate, and a method of manufacturing an organic light-emitting display apparatus. The vapor deposition apparatus includes a chamber including an exhaust port; a stage disposed in the chamber, and including a mounting surface on which the substrate is to be disposed; an injection portion including at least one injection opening through which a gas is injected in a direction parallel with a surface of the substrate on which the thin film is to be formed; and a plasma generator disposed apart from the substrate to face the substrate.