EGR control unit and EGR control method

The present invention relates to an EGR control unit and EGR control method for controlling an EGR adjusting apparatus (10), and it is an object of the invention to calculate an EGR rate at a low cost and to control an operation of the EGR apparatus (10) with high accuracy. The EGR control unit is made up of temperature detecting devices detect in-passage temperature at least two of passages of an intake passage (2b), an atmospheric air introduction passage (2a) located on the upstream side of the intake passage (2b) and communicated with the atmosphere and an EGR passage (4), an actual EGR rate calculating device (32) for calculating a rate of an exhaust gas to an intake gas in an internal combustion engine (1) on the basis of information on temperatures detected by the temperature detecting devices, and an EGR controller (30) for controlling the EGR adjusting device (10) through the use of the actual EGR rate calculated by the actual EGR rate calculating device (32)