CONTROL DEVICE FOR INTERNAL COMBUSTION ENGINE

When alcohol mixing fuel is supplied to an internal combustion engine, an intake air flow rate Ga is detected (Step 1005), and a basic amplitude amount ± of an upstream target air-fuel ratio abyfr corresponding to this detected intake air flow rate Ga is calculated (Step 1010). Next, alcohol concentration in the fuel (in more detail, ethanol concentration Cetha) and a cooling water temperature THW (or an intake air temperature THA) are detected (Step 1015), hydrogen concentration Ch in a mixing exhaust gas is calculated based on the detected ethanol concentration Cetha and the detected cooling water temperature THW (or the detected intake air temperature THA) (Step 1020), amplitude gain ² corresponding to the calculated hydrogen concentration Ch is calculated (Step 1025), and finally, an amplitude amount (± x ²) of the upstream target air-fuel ratio abyfr is calculated (Step 1030).