Atmosphere opening method of treatment container, and storage medium

The subject of the present invention provides an atmosphere opening method of a treatment container capable of opening the treatment container into the atmosphere with less generation of hazardous gas such as HF even when a byproduct consisting of metal fluoride is deposited in the treatment container. To solve the problem, there provides an atmosphere opening method of the treatment container for opening the treatment container with a metal fluoride deposited thereon into the atmosphere by performing the predetermined processing therein, which is characterized in that a first operation is repeated a plurality of times, in which the atmosphere is introduced into the treatment container, the metal fluoride is reacted with water in the atmosphere for the sufficient time, and the atmosphere is exhausted. Afterwards, a second operation is repeated a plurality of times, in which the atmosphere is introduced into the treatment container, and exhausted to discharge the reaction product mainly generated by the first