To provide a new vapor growth device with significantly improved safety.

The vapor growth device is provided with: a first channel which supplies gas required for film-formation so as to form a film on a wafer stored in a chamber 103 by a vapor growth method; a second channel which supplies cleaning gas into the chamber in order to clean inside the chamber; and a third channel for exhausting the gas in the chamber. A fourth channel is provided in parallel with the third channel. A gas storage having almost the same atmosphere as that in the chamber is connected to the fourth channel. An exhaust pump is connected to one side of the gas storage. A gas measuring device for measuring a gas atmosphere in the gas storage is connected to the other side of the gas storage.