A substrate processing apparatus includes a holding device that includes a conductive member and holds a substrate, a conduction path structure that includes a conductive material and positioned such that the conduction path structure is in contact with the holding device, a supply device that supplies a processing liquid to the substrate held by the holding device, and a grounding structure including a variable resistance device that changes a resistance such that the grounding structure has a first end portion connected the conduction path structure and a second end portion connected to a ground potential.