Abstract: A heating device for an exhaust catalyst includes a first antenna and a second antenna. The heating device executes a specific radiation control for controlling operation of an electromagnetic wave generator to set a radiation state of an electromagnetic wave from the first antenna to be a different state from a radiation state of an electromagnetic wave from the second antenna. In such a case, the heating device acquires an intensity of an electromagnetic wave, of electromagnetic waves incident on the first antenna, and acquires an intensity of an electromagnetic wave, of electromagnetic waves incident on the second antenna. The heating device acquires a first temperature-correlated value for the first part based on the first electromagnetic wave intensity, and acquires a second temperature-correlated value for the second part based on the second electromagnetic wave intensity.