Disclosed are a substrate processing apparatus and a substrate processing method. The substrate processing apparatus includes an emissivity setting unit to which emissivity at a liquid chemical which is brought into contact with a substrate or emissivity at an interface at which the substrate and the liquid chemical are in contact with each other is input, a radiant energy input unit to which radiant energy radiating from the liquid chemical or the interface is input, and a calculation unit that calculates a calculation temperature of the liquid chemical or the interface based on the emissivity and the radiant energy.