To provide a fluid jet controller to which the opening change of a picking nozzle at its jet-starting or finishing time can suitably be set in response to weaving conditions in a simple constitution to control the jet.

This fluid jet controller is characterized by comprising a throttle valve capable of changing the quantity of a fluid supplied to a nozzle for acting on wefts, a setter for setting a pattern for jetting the fluid from the nozzle in one picking cycle period, and a control circuit for outputting opening signals showing the openings of the throttle valve in response to the rotation angles of a loom on the basis of the jetting pattern set to the setter, wherein the opening change of the picking nozzle at its jet-starting or finishing time is set to the setter as the jetting pattern.