Substrate processing apparatus

To provide a technology that can increase the amount of cassettes stored without increasing the size of a transport device. A substrate processing apparatus according to an aspect of the present disclosure includes a loading/unloading portion having a first side surface through which a container containing a substrate is loaded/unloaded, and a second side surface opposite to the first side surface, a substrate transport portion extending along a first direction orthogonal to the second side surface, and a plurality of batch processing portions adjacent to each other along the longitudinal direction of the substrate transport portion, and the loading/unloading portion includes a first transport device and a second transport device capable of transporting the container, a first area accessible by the first transport device and including a plurality of first storage shelves for storing the containers, a second area accessible by the second transport device and including a plurality of second storage shelves for