A semiconductor manufacturing apparatus and substrate processing method includes a step of acquiring a measurement value based on a first detecting and a second detecting section and determining a first difference of measurement values between the first detecting section and the second detecting section, comparing between a previously stored second difference between measurement values concerning the first detecting section and the second detecting section, calculating a correction value for a pressure in a cooling-gas passage provided between a process chamber and a heating device depending upon the first difference when the first difference is different from the second difference, and correcting the pressure value based on the pressure correction value, and a step of processing the substrate by flowing a cooling gas through the cooling-gas passage while heating the process chamber, and placing the heating device and the cooling device under a control section depending upon a pressure value corrected.