Treatment solution supply method, non-transitory computer-readable storage medium, and treatment solution supply apparatus

A treatment solution supply method includes: a degassed treatment solution generating step of degassing a treatment solution by a degassing mechanism to generate a degassed treatment solution; a treatment solution storing step of storing the degassed treatment solution in a container; a filter solution-passing step of bringing a downstream side from a filter connected to a downstream side from the container via a treatment solution supply pipe to a negative pressure with respect to a pressure in the container to pass the treatment solution in the container through the filter; and a negative pressure maintaining step of maintaining a state in which the downstream side from the filter is brought to the negative pressure, for a predetermined period, after stopping supply of the treatment solution from the container to the filter.