Abstract: A fluid-flow controlling apparatus having a fluid-flow stopping state and a fluid-flowing state, wherein the valve body can be held positively at a determined position thereby to prevent any fluid leaks even when the pressure of supplied fluid is increased, said apparatus is characterized by: valve casing connected to the end of a fluid-supplying tube and comprising a valve seat and a slidable valve body; a reciprocating arm which is restricted by means of stoppers in its movement vertical to the flow direction in said valve casing; a connecting plate for connecting said valve body and said reciprocating arm together, said connecting plate being located in a direction parallel to said flow direction in said fluid-flow stopping state; a link mechanism for connecting a float to said reciprocating arm.