An EGR cooler comprising a tube (3) and a shell (1) surrounding the tube (3) and being designed to supply or discharge a cooling water (9) to or from the interior of the shell (1) and introduce an exhaust gas (10) into the tube (3) from the diesel engine for heat exchanging the exhaust gas (10) with the cooling water (9), wherein a bypass flow path for guiding the cooling water (9) is installed in the shell (1) so as to eliminate any stagnation of the cooling water (9) in the shell (1).
