The present invention discloses an ejector, a housing (170, 263, 380) of the ejector is configured into a tubular form and receives at least a portion of an ejector functional unit (160, 260, 360), which includes a nozzle (161, 261, 361) and a body (162, 262, 362). A housing side opening (165c, 263a, 364a) radially penetrates through an outer peripheral wall surface and an inner peripheral wall surface of the housing (170, 263, 380) and communicates with the fluid suction opening (162b, 262b, 362b) of the body (162, 262, 362). The housing side opening (165c, 263a, 364a) is adapted to join with a suction opening side external device (15b), through which the fluid is drawn into the fluid suction opening (162b, 262b, 362b).