PROBLEM TO BE SOLVED: To provide a feeder for a chemical solution with a structure improving a suction mixture action to a stream of the chemical solution in which the feeder for a chemical solution is interposed in irrigation water piping for a field and the like and liquid chemical is sucked by negative pressure generated by a venturi action to mix the liquid chemical into the stream in the piping.SOLUTION: A feeder for an agricultural chemical solution interposed in irrigation water piping comprises: an outer cylindrical body including an upstream side end part and a downstream side end part which are connected with the water piping and an inner cylindrical body which is combined with an inner peripheral side of the upstream side end part in the outer cylindrical body. A negative pressure chamber is formed in a flow channel between the outer cylindrical body and the inner cylindrical body, in which velocity of the stream is increased by decreasing sectional area to generate negative pressure. An inflow hole for a chemical solution is formed at a peripheral wall of the outer cylindrical body in which the inflow hole is communicated with an external chemical solution vessel at one end part, and opened to the negative pressure chamber of the flow channel at the other end part. The inflow hole is slanted to approach a downstream end part of the outer cylindrical body as approaching an axial center of the outer cylindrical body.
