The invention relates to an exhaust gas turbocharger having a fluid dynamic bearing having a rotor (10) and a counter-bearing part (50) assigned to the rotor (10), wherein a rotor bearing surface of the rotor (10) and a counterface of the counter-bearing part (50) face each other, to form a fluid dynamic bearing, wherein the rotor bearing surface and/or the counterface form(s) a continuous bearing contour when cut longitudinally and through the axis of rotation (R) in sectional view, which bearing contour(s) are formed of at least two contour sections (44.1 to 44.3; 53.1 to 53.3) to generate fluid dynamic load capacities in both the radial and the axial directions, wherein the bearing surface of the rotor (10) is formed by a rotor part (40), which is connected to a rotor shaft (11) and is secured on the rotor shaft (11), and wherein the rotor part (40) is supported relative to the rotor shaft (11) in the area of a support section (14) of the rotor shaft (11). In order to be able to provide such an exhaust gas turbocharger with a compact and efficient bearing arrangement having a fluid dynamic bearing, wherein at the same time the fluid dynamic bearing can be easily mounted using few parts, provision is made according to the invention that the support section (14) and at least one of the contour sections (53.1 to 53.3) of the counter-bearing part (50) at least sectionally overlap in the direction of the axis of rotation (R).