There is provided a substrate warping monitoring device for monitoring a warping of a substrate mounted in a substrate mounting region formed in a rotary table along a circumferential direction during rotation of the rotary table, including: an optical displacement meter located above the rotary table and configured to irradiate a light to a predetermined position on the rotary table, receive a reflected light reflected off the rotary table and the substrate which passes through the predetermined position and measure a surface profile of the substrate; a memory part configured to store a measurement value acquired when the light is irradiated on a predetermined reference surface, as a reference value; and a calculation part configured to calculate a warping amount of the substrate based on the surface profile of the substrate measured by the optical displacement meter and the reference value stored in the memory part.