A substrate processing apparatus includes: a substrate holder to hold a substrate in a horizontal posture while rotating the substrate about a vertical rotary axis passing through the center of a plane of the substrate; a guard member having a shape extending along at least part of a surface peripheral area of the substrate, the guard member being placed in a position close to the surface peripheral area of the substrate held by the substrate holder in a noncontact manner; a cup being a tubular member with an open top end, the cup being provided so as to surround the substrate held by the substrate holder and the guard member together; and a nozzle from which a processing liquid is discharged to the surface peripheral area of the substrate held by the substrate holder. The nozzle is placed on a side opposite the cup with respect to at least part of the guard member.