An angle-measuring device including a first component group and a second component group, the component groups being disposed in a manner allowing rotation relative to each other by a bearing. The first component group includes a housing having a connecting device, as well as a scanning unit. The second component group includes a shaft to which a code disk is attached, and a flow channel having a directional component parallel to the axis. The angle-measuring device is configured such that a negative pressure is able to be applied to the connecting device, so that a fluid surrounding the angle-measuring device with a pressure flows through the angle-measuring device to remove contaminants by suction. At the applied negative pressure, a first mass flow of the fluid which flows through the flow channel is greater than a second mass flow which flows through the bearing gap.