Provided is an internal combustion engine control device capable of reducing a measurement load and calculating a flow velocity around an ignition plug. The internal combustion engine control device includes an inter-gap voltage calculation unit 31 and a flow velocity calculation unit 32. The inter-gap voltage calculation unit 31 calculates a reference inter-gap voltage under a reference condition, based on a secondary current and in-cylinder pressure. The flow velocity calculation unit calculates the flow velocity of a gas around the ignition plug based on the reference inter-gap voltage.