The present invention is used at a control site in a rural area, and agitation and mixing of water and a control agent inside a chemical liquid container using a pressure control valve and a return hose, as well as control using a chemical solution of an external chemical liquid container using a three-way valve It is related to an agricultural sprayer that makes it easy to control the mixing ratio of water and a pharmaceutical, It is formed in a form that can be carried by the user on the back, and the liquid container is provided with an inlet on one side of the upper side； It includes； a spray device provided inside the lower portion of the chemical liquid container to spray the chemical liquid by using a battery-operated injection pump, the chemical liquid container and the upper chemical liquid tank by the separation plate at a certain distance from the bottom It is divided into a lower case provided with a spraying device, and the spraying device includes a chemical liquid supply pipe through which a chemical liquid of a chemical liquid tank is supplied, an external chemical liquid supply pipe through which an external chemical liquid is supplied, and a chemical liquid spray pipe through which a chemical liquid is sprayed, and a motor. It is driven by the injection pump for feeding the chemical liquid to the chemical spray tube, and provided in the connection portion of the chemical liquid supply pipe and the external chemical liquid supply pipe, and the chemical liquid control member for selectively supplying the chemical liquid of the chemical liquid tank or the external chemical liquid container to the injection pump, injection A return hose for returning the chemical liquid sent from the pump to the chemical liquid tank, and a pressure interruption valve provided at the connection portion of the chemical liquid spray tube and the return hose to block the chemical liquid from being sprayed through the chemical liquid spray tube and return to the chemical li
