A footswitch for a medical instrument, with a housing, and with an elastically deformable suction cup arranged in the housing, where a negative pressure is generated in the suction cup by means of an evacuation device in order to secure the housing to a floor surface. In order to create a footswitch which is suitable for a medical instrument and which, while having a simple design and being easy to handle, ensures that the footswitch is secured in a fixed position on a floor surface. The suction cup is elastically extensible via the evacuation device in order to generate the negative pressure by enlargement of the volume enclosed by the suction cup.