A spark ignition engine control apparatus for a spark ignition engine, comprising: an input unit which receives a first signal indicating a state of exhaust gas in an inside or downstream of a particulate filter trapping particulate substances contained in the exhaust gas of a spark ignition engine; and a determination unit which determines whether the particulate filter is degraded, on the basis of the state of the exhaust gas indicated by the first signal, in a period in which fuel supply to the spark ignition engine is blocked when the spark ignition engine rotates and air flows into the particulate filter , wherein the spark ignition engine control apparatus includes one of the following configurations a or b: a) the first signal indicates an oxygen concentration of the exhaust gas in the inside or downstream of the particulate filter , and the determination unit determines that the particulate filter is degraded, when a state in which the oxygen concentration is equal to or larger than a second threshold value continues for a second period; b) the first signal indicates a carbon dioxide concentration in the inside or downstream of the particulate filter, and the determination unit determines that the particulate filter is degraded, when a state in which the carbon dioxide concentration is equal to or smaller than a third threshold value continues for a third period. an input unit which receives a first signal indicating a state of exhaust gas in an inside or downstream of a particulate filter trapping particulate substances contained in the exhaust gas of a spark ignition engine; and a determination unit which determines whether the particulate filter is degraded, on the basis of the state of the exhaust gas indicated by the first signal, in a period in which fuel supply to the spark ignition engine is blocked when the spark ignition engine rotates and air flows into the particulate filter , wherein the spark ignition engine control apparatus includes one of the following configurations a or b: a) the first signal indicates an oxygen concentration of the exhaust gas in the inside or downstream of the particulate filter , and the determination unit determines that the particulate filter is degraded, when a state in which the oxygen concentration is equal to or larger than a second threshold value continues for a second period; b) the first signal indicates a carbon dioxide concentration in the inside or downstream of the particulate filter, and the determination unit determines that the particulate filter is degraded, when a state in which the carbon dioxide concentration is equal to or smaller than a third threshold value continues for a third period. a) the first signal indicates an oxygen concentration of the exhaust gas in the inside or downstream of the particulate filter , and the determination unit determines that the particulate filter is degraded, when a state in which the oxygen concentration is equal to or larger than a second threshold value continues for a second period; b) the first signal indicates a carbon dioxide concentration in the inside or downstream of the particulate filter, and the determination unit determines that the particulate filter is degraded, when a state in which the carbon dioxide concentration is equal to or smaller than a third threshold value continues for a third period. <EOS>