The invention relates to a sensor element, in particular for detecting a physical property of a gas, in particular for detecting the concentration of a gas component or the temperature or a solid constituent or a liquid constituent of an exhaust gas of an internal combustion engine. The sensor element (20) has, for example, a solid electrolyte film (21) and has a first end region and a second end region (202) opposite each other in a longitudinal direction of the sensor element. The sensor element (20) has a functional element outside of the second end region (202), in particular in the first end region, which functional element is connected in an electrically conductive manner to a contact surface (43, 44) arranged on the outer surface of the sensor element (20) in the second end region (202). The sensor element is characterized in that the contact surface (43) is rounded, for example with a radius (R), on the side of the contact surface facing away from the first end region (201). The contact surfaces (43, 44) comprise, in particular, three partial regions: head region (432, 442), neck region (433, 443), and torso region (431, 441).