A controller for an internal combustion engine including a plurality of cylinders, a fuel injection valve for supplying a fuel to each cylinder, an EGR passage connecting an exhaust passage and an intake passage, and an EGR valve adjusting a flow rate of exhaust flowing into the intake passage from the exhaust passage via the EGR passage, the controller includes an electronic control unit. The electronic control unit is configured to execute determination processing for determining that a degree of an imbalance abnormality is larger when a torque fluctuation amount is relatively large than when the torque fluctuation amount is relatively small.