A heating device for an exhaust catalyst disposed in an exhaust passage of an internal combustion engine, the exhaust catalyst being configured to generate heat by absorbing an electromagnetic wave, the heating device including at least one electromagnetic wave generator configured to generate an electromagnetic wave and a first antenna disposed in use close to a first part of the exhaust catalyst and an electronic control device, the first antenna being configured to radiate an electromagnetic wave generated by the electromagnetic wave generator to the first part, the heating device characterized by comprising: a second antenna disposed in use close to a second part of the exhaust catalyst different from the first part, the second antenna being disposed at a predetermined interval from the first antenna, the second antenna being configured to radiate an electromagnetic wave generated by the electromagnetic wave generator to the second part; wherein the electronic control device is configured to execute a catalyst temperature increasing control for increasing the temperature of the exhaust catalyst by controlling the electromagnetic wave generator to radiate the electromagnetic wave to the first part and the second part from the first antenna and the second antenna respectively, execute a specific radiation control for controlling operation of the electromagnetic wave generator to set a radiation state of the electromagnetic wave from the first antenna to be a different state from a radiation state of the electromagnetic wave from the second antenna, acquire the intensity of an electromagnetic wave, of electromagnetic waves incident on the first antenna at the execution of the specific radiation control, which corresponds to the radiation state of the electromagnetic wave radiated from the first antenna as a first electromagnetic wave intensity, acquire the intensity of an electromagnetic wave, of electromagnetic waves incident on the second antenna at the execution of the specific radiation control, which corresponds to the radiation state of the electromagnetic wave radiated from the second antenna as a second electromagnetic wave intensity, acquire, based on the first electromagnetic wave intensity, a first temperature-correlated value that is a value correlated with the temperature of the first part, acquire, based on the second electromagnetic wave intensity, a second temperature-correlated value that is a value correlated with the temperature of the second part, and when the first temperature-correlated value and the second temperature-correlated value are different from each other, control the operation of the electromagnetic wave generator to adjust at least one of the intensity and the output duty cycle of the electromagnetic wave radiated from at least one of the first antenna and the second antenna such that the deviation between the first temperature-correlated value and the second temperature-correlated value is decreased in the catalyst temperature increasing control. a second antenna disposed in use close to a second part of the exhaust catalyst different from the first part, the second antenna being disposed at a predetermined interval from the first antenna, the second antenna being configured to radiate an electromagnetic wave generated by the electromagnetic wave generator to the second part; wherein the electronic control device is configured to execute a catalyst temperature increasing control for increasing the temperature of the exhaust catalyst by controlling the electromagnetic wave generator to radiate the electromagnetic wave to the first part and the second part from the first antenna and the second antenna respectively, execute a specific radiation control for controlling operation of the electromagnetic wave generator to set a radiation state of the electromagnetic wave from the first antenna to be a different state from a radiation state of the electromagnetic wave from the second antenna, acquire the intensity of an electromagnetic wave, of electromagnetic waves incident on the first antenna at the execution of the specific radiation control, which corresponds to the radiation state of the electromagnetic wave radiated from the first antenna as a first electromagnetic wave intensity, acquire the intensity of an electromagnetic wave, of electromagnetic waves incident on the second antenna at the execution of the specific radiation control, which corresponds to the radiation state of the electromagnetic wave radiated from the second antenna as a second electromagnetic wave intensity, acquire, based on the first electromagnetic wave intensity, a first temperature-correlated value that is a value correlated with the temperature of the first part, acquire, based on the second electromagnetic wave intensity, a second temperature-correlated value that is a value correlated with the temperature of the second part, and when the first temperature-correlated value and the second temperature-correlated value are different from each other, control the operation of the electromagnetic wave generator to adjust at least one of the intensity and the output duty cycle of the electromagnetic wave radiated from at least one of the first antenna and the second antenna such that the deviation between the first temperature-correlated value and the second temperature-correlated value is decreased in the catalyst temperature increasing control.