To provide a heat quantity adjustment method of hydrate capable of taking out a mixed gas in substantially the same state with a mixed gas before hydrate even in the case the gas mixture composed of a plurality of kinds of gasses is hydrated and preserved.

When a gas mixture of a plurality of kinds of gasses is hydrated and preserved, the hydrate is generated at every component of the gas mixture and dividedly preserved in corresponding preservation containers 28, 30, 32, 34. Thereafter, when the gas mixture is taken out of the hydrate, the hydrate is discomposed in corresponding preservation containers and component gasses diffused from the corresponding preservation container are mixed to get a specified mixing ratio and the gas mixture is taken out.