To provide an apparatus for sucking a chemical agent pressurizing it in a pump and mixing to perform chemical agent spray while attain an almost fixed dilution even if the spray quantity is changed.

This spray apparatus has a nozzle attached to the end part of a main passage, a check valve with a throttle valve to prevent the backward flow to a fresh tank in the leading part of the main passage, the pump for sucking and pressurizing the fresh water, a control valve attached to the pump, a spillway for returning the spilling water from the control valve to a water sucking pipe, and a chemical agent passage for injecting the chemical agent to the water sucking pipe of the main passage, and the quantity of the chemical agent proportional to the spray quantity from the nozzle is injected to the main passage.