An exhaust gas control system for an internal combustion engine comprising: a housing disposed in an exhaust passage of the internal combustion engine; an exhaust gas purification catalyst disposed in the housing, the exhaust gas purification catalyst configured to purify exhaust gas of the internal combustion engine; and a microwave irradiator disposed on an upstream side or a downstream side of the exhaust gas purification catalyst in the exhaust passage, characterized in that the microwave irradiator configured to irradiate the exhaust gas purification catalyst with a microwave at a specified frequency, preferably 2.45 GHz, such that a standing wave is formed in the housing by the microwave, said standing wave having: a high magnetic field region where magnetic field intensity is high and becomes at least equal to a specified rate (IHTH) of a maximum value of the magnetic field intensity; and a high electric field region where electric field intensity is high and becomes at least equal to a specified rate (IETH) of a maximum value of the electric field intensity, wherein a position where the magnetic field intensity of the standing wave reaches the maximum value and a position where the electric field intensity of the standing wave reaches the maximum value differ from each other, the exhaust gas purification catalyst includes a carrier substrate and a catalytic substance that purifies the exhaust gas, the catalytic substance is disposed on the carrier substrate, the carrier substrate includes a magnetic body region having a magnetic body and a dielectric region having a dielectric, the magnetic body region of the carrier substrate is disposed in the high magnetic field region in the housing, the dielectric region of the carrier substrate is disposed in the high electric field region in the housing, wherein a material of the magnetic body differs from a material of the dielectric, and the magnetic body absorbs the microwave, and the dielectric absorbs the microwave. a housing disposed in an exhaust passage of the internal combustion engine; an exhaust gas purification catalyst disposed in the housing, the exhaust gas purification catalyst configured to purify exhaust gas of the internal combustion engine; and a microwave irradiator disposed on an upstream side or a downstream side of the exhaust gas purification catalyst in the exhaust passage, characterized in that the microwave irradiator configured to irradiate the exhaust gas purification catalyst with a microwave at a specified frequency, preferably 2.45 GHz, such that a standing wave is formed in the housing by the microwave, said standing wave having: a high magnetic field region where magnetic field intensity is high and becomes at least equal to a specified rate (IHTH) of a maximum value of the magnetic field intensity; and a high electric field region where electric field intensity is high and becomes at least equal to a specified rate (IETH) of a maximum value of the electric field intensity, wherein a position where the magnetic field intensity of the standing wave reaches the maximum value and a position where the electric field intensity of the standing wave reaches the maximum value differ from each other, the exhaust gas purification catalyst includes a carrier substrate and a catalytic substance that purifies the exhaust gas, the catalytic substance is disposed on the carrier substrate, the carrier substrate includes a magnetic body region having a magnetic body and a dielectric region having a dielectric, the magnetic body region of the carrier substrate is disposed in the high magnetic field region in the housing, the dielectric region of the carrier substrate is disposed in the high electric field region in the housing, wherein a material of the magnetic body differs from a material of the dielectric, and the magnetic body absorbs the microwave, and the dielectric absorbs the microwave. a high magnetic field region where magnetic field intensity is high and becomes at least equal to a specified rate (IHTH) of a maximum value of the magnetic field intensity; and a high electric field region where electric field intensity is high and becomes at least equal to a specified rate (IETH) of a maximum value of the electric field intensity, wherein a position where the magnetic field intensity of the standing wave reaches the maximum value and a position where the electric field intensity of the standing wave reaches the maximum value differ from each other, the exhaust gas purification catalyst includes a carrier substrate and a catalytic substance that purifies the exhaust gas, the catalytic substance is disposed on the carrier substrate, the carrier substrate includes a magnetic body region having a magnetic body and a dielectric region having a dielectric, the magnetic body region of the carrier substrate is disposed in the high magnetic field region in the housing, the dielectric region of the carrier substrate is disposed in the high electric field region in the housing, wherein a material of the magnetic body differs from a material of the dielectric, and the magnetic body absorbs the microwave, and the dielectric absorbs the microwave.