The invention concerns an apparatus for gravimetric dosing of powder material from a container. The apparatus comprises a container (1) and a valve located in a flow channel of material flowing from the discharge aperture of the container, said valve being provided for opening and closing the flow channel. The valve comprises a flow aperture (2) and a shutter movable with a sliding tolerance back and forth in the aperture. The shutter is a plug (3) movable in the perpendicular direction with respect to the plane of the aperture, having a length in the flow direction of the valve and having an envelope surface forming a sliding surface equivalent to the periphery of the flow aperture (2). In the sliding surface there is at least one groove (4) expanding in the flow direction of the valve.