PROBLEM TO BE SOLVED: To efficiently cool a processed substrate, relating to heating process in which microwave is introduced into a process container for heating the processed substrate.SOLUTION: A microwave heating processing apparatus 1 includes a support stage 13 for supporting a wafer W in a process container 10, a microwave introducing mechanism 11 for introducing microwave into the process container 10, a coolant flow passage 35 formed inside the support stage 13, and a coolant supply source 34 for supplying coolant to a coolant flow passage 35. At least a surface of the support stage 13 which supports the wafer W is made from a material of which a product of dielectric constant and a dielectric loss angle is less than 0.005. The coolant supplied from the coolant supply source 34 is a liquid which does not have electrical polarity.