Abstract: An oil gun for an automatic fluid pump conveniently supplies fluid stored inside a tank to the inside of a container. The oil gun includes a case and a handle part, which has a switch to control a battery-operated suction pumping part coupled to a suction hose to which a supply hose is coupled. A gun nozzle coupling part curvedly extends downward from the handle part. The case is divided into an upper case and a lower case that can be assembled and disassembled. A first seating groove is formed on one end of each of the upper case and the lower case to receive a connector of a flow path member. A second seating groove is formed on the other end of each of the upper case and the lower case to receive an upper portion of the gun nozzle.