Surface treatment liquid, surface treatment method, and method for suppressing pattern collapse

A surface treatment liquid capable of hydrophobizing a surface of a treatment target without including a silylation agent, a surface treatment method using the liquid, and a method for suppressing pattern collapse, including surface treatment by the surface treatment method. The liquid contains a nitrogen-containing heterocyclic compound as a water-repelling agent. A compound including one or more hydrocarbon groups which may be substituted with a halogen atom in which a total number of carbon atoms of the one or more hydrocarbon group is three or more, is used as the nitrogen-containing heterocyclic compound. The liquid may include only a nitrogen-containing heterocyclic compound having the above-described predetermined structure, as a water-repelling agent.