Control Device for Internal Combustion Engine

A processor (CPU ) of a control device (ECU ) for an internal combustion engine identifies a first throttle valve opening degree θand a second throttle valve opening degree θat which a change rate (differential value) of an index (a deposit thickness, a decrease rate of an effective opening area, a flow rate decrease rate, and the like) correlated with a decrease rate of an effective opening area of a throttle valve changes (s). The processor (CPU ) estimates an index at any throttle valve opening degree from the first throttle valve opening degree θand the second throttle valve opening degree θ(s), and calculates an effective opening area of the throttle valve from the estimated index (s).