To reduce an amount of a gas refrigerant flowing out from a refrigerant storage vessel with a liquid refrigerant and thereby inhibit the performance deterioration of an air conditioner without using a partition plate of the refrigerant storage vessel which is connected with a refrigerant circuit in the air conditioner including the refrigerant circuit which is formed so that a circulation direction of the refrigerant is reversible.

A refrigerant storage vessel (10) is provided with: a vessel body (11) having one internal space; a first pipeline (1) which is connected with a first expansion valve (33) and in which a lower end opening (3) positioned at the lower side of a liquid surface placed during heating operation is formed; and a second pipeline (2) which is connected with a second expansion valve (34) and in which a lower end opening (4) positioned between a liquid surface placed during cooling operation and a liquid surface placed during the heating operation is formed.