A canteen is composed of a main body, a cover, a control unit, a valve and an annular blocker. The cover is engaged with the main body, having a jointing tube protruding into the main body and two notches cut in the jointing tube. The control unit is fixed on the cover, having a jointing portion, two grooves formed in the jointing portion and reversely shaped to correspond to the notches of the cover, and a sucker bored with an outlet. The valve is installed in the control unit, having a bar to correspond to the outlet, and a guiding rod transversely extended out from its bottom to extend through the grooves and the notches of the cover. When rotating the control unit, the valve is moved up and down to be separated from or to clog the outlet, convenient for using and preventing the suction portion from contaminated.