There is provided a chemical vapor deposition apparatus improved in structure such that a reaction gas introduced into a reactor where deposition is performed flows at a substantially uniform rate to ensure a thin film is grown substantially uniformly on the deposition object. The chemical vapor deposition apparatus includes: a chamber; a reactor provided in the chamber to have a deposition object deposited therein; and a reservoir storing a reaction gas fed from the outside to introduce the reaction gas to the reactor, the reservoir having a cross-sectional area changing according to a flow path of the introduced reaction gas.