Substrate processing apparatus and operation method of substrate processing apparatus

A plasma processing apparatus includes a storage; processors; a liquid supply which supplies, into the storage, at least a first liquid composed of a processing liquid or source liquids for composing the processing liquid; a detector which detects a value of a parameter indicating a state of the first liquid supplied into the storage or a state of the processing liquid in the storage; and a controller which controls the processors to perform a liquid processing in sequence. The controller determines, based on a detection result of the value of the parameter, whether it is possible to supply the processing liquid continuously into a preset number of processors concurrently under a condition requested by the processors, and, if not, the controller performs a simultaneous processing restricting control of reducing a number of processors which are supposed to perform the liquid processing concurrently to be lower than the preset number.