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.