To provide a minute-quantity-of-gas supplying apparatus which can supply minute quantity of gas highly precisely.

The minute quantity of gas supplying apparatus comprises: a source 22 of gas to be controlled for storing gas to be controlled; a career gas source 20 for storing career gas; a career gas passage 24 connected to a gas using system 4 from the career gas source; a gas discharge passage 30 for discharging the gas to be controlled; a quantity pipe 32 which has predetermined minute volume and is connected to the career gas passage and the gas discharge passage in parallel; and a valve mechanism 38 which selectively switches a communication state of the quantity pipe between both passages. Thereby the gas to be controlled charged in the quantity pipe is supplied to the gas using system and minute quantity of gas flow can be controlled highly precisely.