An ejector pump is provided which works to use dynamic energy of a jet of a main fluid emitted from a nozzle to suck a sub-fluid therein. When it is required to stop the ejector pump, the needle is moved to bring a sealing surface formed on a head thereof into abutment with a sealing surface formed around a main fluid flow path extending inside the ejector pump to close the main fluid flow path, thereby inhibiting the fluid pressure from acting on any downstream device. Upon the abutment, the needle is kept away from a nozzle, thereby avoiding undesirable wear or deformation of the needle and nozzle.