Abstract: The closure for a drinking flask comprises a closing cap (2) mountable onto a drinking flask opening and a shut-off and opening device (K) which includes a stationary part (4) which is stationary relative to the closing cap (2) and a sliding part (5) which is displaceable relative to the closing cap (2) which is moveable from a shut-off position into a drinking position in which liquid present in the drinking flask (1) can exit the drinking flask (1). The sliding part (5) is arranged around the stationary part (4), at least one restoring device (9) acts with a force directed away from the closing cap (2) towards the outside onto the sliding part (5). The sliding part (5) is located in the shut-off state in a outer position and is to be moved for the transition from the shut-off position into the drinking position inwards towards the closing cap (1) against the resistance of the at least one restoring device (9) into an inner position.