The disclosure provides a substrate processing apparatus that processes a surface of a substrate with a processing fluid in a supercritical state, in which the substrate is protected from the pressure fluctuation caused by partial vaporization of the processing fluid in the flow path. A substrate processing apparatus which processes a surface of a substrate with a processing fluid in a supercritical state includes a chamber housing provided therein with a processing space capable of housing the substrate and a flow path which receives the processing fluid from outside and guides the processing fluid to the processing space, and a fluid supply part which pressure-feeds the processing fluid to the flow path, wherein a plurality of bent parts which change a flow direction of the processing fluid are provided in the flow path.