A chemical vapor deposition apparatus is equipped to control the width of a gas discharge path between a susceptor and an inner surface of a chamber without having to resort to redesign and remanufacturing of the apparatus. The chemical vapor deposition apparatus includes: a chamber; a susceptor positioned inside the chamber and on which a substrate can be loaded; a shower head injecting a processing gas toward the substrate; and a guide unit detachably installed inside the chamber to guide the processing gas such that the processing gas injected from the shower head is discharged through a chamber hole formed in the chamber.