A valve mechanism for a suction instrument or an irrigation instrument includes a valve object a first piston moveably disposed in the valve object a second piston moveably disposed in the valve object and a piston buckling unit pivoting on an outside of the valve object. When the first piston is pressed, the first piston moves downward, and a first buckle on the first piston is fixed on a third buckle of the piston buckling unit to open an irrigating pathway. When the second piston is pressed, the second piston moves downward, and a second buckle on the second piston is fixed on another third buckle of the piston buckling unit to open a suction pathway.
