Processing method, method of manufacturing semiconductor, and substrate processing apparatus

Described is a technique capable of optimizing a timing of a maintenance process. According to one aspect, there is a method of manufacturing a semiconductor device including: (a) transferring a substrate to a process chamber, and performing substrate processing; (b) receiving maintenance reservation information of the process chamber; (c) continuously performing the substrate processing related to the received maintenance reservation information, stopping a next substrate from being transferred into the process chamber after the substrate processing is completed, and thereafter setting the process chamber to the maintenance enable state; (d-1) receiving an instruction of advancing or delaying the maintenance timing within a predetermined range; and (d-2) starting the next substrate processing without setting the process chamber to the maintenance enable state when the instruction of delaying the maintenance timing is received in (d-1), and terminating the substrate processing when the instruction of advancing the maintenance timing is received in (d-1).