The invention relates to a valve device for medical instruments, in particular trocars, having a valve body configured as a flap for opening and closing an instrument and/or flow channel, which is positioned rotatably on a rotation axle positioned in a housing. To create a valve device, which combines simple and cost-effective structure with good cleaning properties, it is proposed with the invention that the rotation axle is configured in several components, such that the individual components of the rotation axle can be connected to one another by helical-shaped guide tracks.