A substrate processing method includes a substrate holding step of horizontally holding a substrate, a substrate rotating step of rotating the substrate held horizontally around a rotational axis along a vertical direction, a liquid-film forming step of forming a liquid film of a first organic solvent that is used to process an upper surface of the substrate on the upper surface of the substrate by supplying the first organic solvent to the upper surface of the substrate held horizontally, a vapor supplying step of supplying a vapor of a second organic solvent to a space between a facing surface of a heater unit that has the facing surface facing a lower surface of the substrate held horizontally and the lower surface of the substrate, a substrate heating step of heating the substrate being in a rotational state by means of the vapor of the second organic solvent in parallel with the substrate rotating step and the liquid-film forming step, and a substrate drying step of, after the substrate heating step, excluding the liquid film of the first organic solvent from the substrate held horizontally and drying the upper surface of the substrate in a state in which the rotation of the substrate is stopped and the substrate is in contact with the heater unit.